[358ec13] | 1 | /*
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| 2 | * Copyright (c) 2007 Vojtech Mencl
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| 3 | * All rights reserved.
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| 4 | *
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| 5 | * Redistribution and use in source and binary forms, with or without
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| 6 | * modification, are permitted provided that the following conditions
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| 7 | * are met:
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| 8 | *
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| 9 | * - Redistributions of source code must retain the above copyright
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| 10 | * notice, this list of conditions and the following disclaimer.
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| 11 | * - Redistributions in binary form must reproduce the above copyright
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| 12 | * notice, this list of conditions and the following disclaimer in the
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| 13 | * documentation and/or other materials provided with the distribution.
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| 14 | * - The name of the author may not be used to endorse or promote products
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| 15 | * derived from this software without specific prior written permission.
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| 16 | *
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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| 27 | */
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| 28 |
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| 29 | /** @addtogroup genericadt
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| 30 | * @{
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| 31 | */
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| 32 |
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| 33 | /**
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| 34 | * @file
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| 35 | * @brief AVL tree implementation.
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| 36 | *
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| 37 | * This file implements AVL tree type and operations.
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| 38 | *
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| 39 | * Implemented AVL tree has the following properties:
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| 40 | * @li It is a binary search tree with non-unique keys.
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| 41 | * @li Difference of heights of the left and the right subtree of every node is
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| 42 | * one at maximum.
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| 43 | *
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| 44 | * Every node has a pointer to its parent which allows insertion of multiple
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| 45 | * identical keys into the tree.
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[ae318d3] | 46 | *
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[358ec13] | 47 | * Be careful when using this tree because of the base atribute which is added
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| 48 | * to every inserted node key. There is no rule in which order nodes with the
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| 49 | * same key are visited.
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| 50 | */
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| 51 |
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| 52 | #include <adt/avl.h>
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[63e27ef] | 53 | #include <assert.h>
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[358ec13] | 54 |
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| 55 | #define LEFT 0
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| 56 | #define RIGHT 1
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| 57 |
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| 58 | /** Search for the first occurence of the given key in an AVL tree.
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| 59 | *
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| 60 | * @param t AVL tree.
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| 61 | * @param key Key to be searched.
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| 62 | *
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| 63 | * @return Pointer to a node or NULL if there is no such key.
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| 64 | */
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[d1e9321] | 65 | avltree_node_t *avltree_search(avltree_t *t, avltree_key_t key)
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[358ec13] | 66 | {
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| 67 | avltree_node_t *p;
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[a35b458] | 68 |
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[358ec13] | 69 | /*
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| 70 | * Iteratively descend to the leaf that can contain the searched key.
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| 71 | */
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| 72 | p = t->root;
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| 73 | while (p != NULL) {
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| 74 | if (p->key > key)
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| 75 | p = p->lft;
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| 76 | else if (p->key < key)
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| 77 | p = p->rgt;
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[1b20da0] | 78 | else
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[358ec13] | 79 | return p;
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| 80 | }
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| 81 | return NULL;
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| 82 | }
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| 83 |
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| 84 | /** Find the node with the smallest key in an AVL tree.
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| 85 | *
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| 86 | * @param t AVL tree.
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| 87 | *
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| 88 | * @return Pointer to a node or NULL if there is no node in the tree.
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| 89 | */
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| 90 | avltree_node_t *avltree_find_min(avltree_t *t)
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| 91 | {
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| 92 | avltree_node_t *p = t->root;
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[a35b458] | 93 |
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[358ec13] | 94 | /*
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| 95 | * Check whether the tree is empty.
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| 96 | */
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| 97 | if (!p)
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| 98 | return NULL;
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[a35b458] | 99 |
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[358ec13] | 100 | /*
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| 101 | * Iteratively descend to the leftmost leaf in the tree.
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| 102 | */
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[1b20da0] | 103 | while (p->lft != NULL)
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[358ec13] | 104 | p = p->lft;
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[a35b458] | 105 |
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[358ec13] | 106 | return p;
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| 107 | }
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| 108 |
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[83a5cba] | 109 | #define REBALANCE_INSERT_XX(DIR1, DIR2) \
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| 110 | top->DIR1 = par->DIR2; \
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| 111 | if (top->DIR1 != NULL) \
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| 112 | top->DIR1->par = top; \
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| 113 | par->par = top->par; \
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| 114 | top->par = par; \
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| 115 | par->DIR2 = top; \
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| 116 | par->balance = 0; \
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| 117 | top->balance = 0; \
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| 118 | *dpc = par;
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| 119 |
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| 120 | #define REBALANCE_INSERT_LL() REBALANCE_INSERT_XX(lft, rgt)
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| 121 | #define REBALANCE_INSERT_RR() REBALANCE_INSERT_XX(rgt, lft)
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| 122 |
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| 123 | #define REBALANCE_INSERT_XY(DIR1, DIR2, SGN) \
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| 124 | gpa = par->DIR2; \
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| 125 | par->DIR2 = gpa->DIR1; \
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| 126 | if (gpa->DIR1 != NULL) \
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| 127 | gpa->DIR1->par = par; \
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| 128 | gpa->DIR1 = par; \
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| 129 | par->par = gpa; \
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| 130 | top->DIR1 = gpa->DIR2; \
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| 131 | if (gpa->DIR2 != NULL) \
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| 132 | gpa->DIR2->par = top; \
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| 133 | gpa->DIR2 = top; \
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| 134 | gpa->par = top->par; \
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| 135 | top->par = gpa; \
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| 136 | \
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| 137 | if (gpa->balance == -1 * SGN) { \
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| 138 | par->balance = 0; \
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| 139 | top->balance = 1 * SGN; \
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| 140 | } else if (gpa->balance == 0) { \
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| 141 | par->balance = 0; \
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| 142 | top->balance = 0; \
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| 143 | } else { \
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| 144 | par->balance = -1 * SGN; \
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| 145 | top->balance = 0; \
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| 146 | } \
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| 147 | gpa->balance = 0; \
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| 148 | *dpc = gpa;
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| 149 |
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| 150 | #define REBALANCE_INSERT_LR() REBALANCE_INSERT_XY(lft, rgt, 1)
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| 151 | #define REBALANCE_INSERT_RL() REBALANCE_INSERT_XY(rgt, lft, -1)
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[a35b458] | 152 |
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[358ec13] | 153 | /** Insert new node into AVL tree.
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| 154 | *
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| 155 | * @param t AVL tree.
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| 156 | * @param newnode New node to be inserted.
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[1b20da0] | 157 | */
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[358ec13] | 158 | void avltree_insert(avltree_t *t, avltree_node_t *newnode)
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[1b20da0] | 159 | {
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| 160 | avltree_node_t *par;
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[358ec13] | 161 | avltree_node_t *gpa;
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| 162 | avltree_node_t *top;
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| 163 | avltree_node_t **dpc;
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[d1e9321] | 164 | avltree_key_t key;
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[358ec13] | 165 |
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[63e27ef] | 166 | assert(t);
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| 167 | assert(newnode);
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[358ec13] | 168 |
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| 169 | /*
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| 170 | * Creating absolute key.
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[1b20da0] | 171 | */
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[358ec13] | 172 | key = newnode->key + t->base;
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[a35b458] | 173 |
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[358ec13] | 174 | /*
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| 175 | * Iteratively descend to the leaf that can contain the new node.
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| 176 | * Last node with non-zero balance in the way to leaf is stored as top -
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| 177 | * it is a place of possible inbalance.
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| 178 | */
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| 179 | dpc = &t->root;
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| 180 | gpa = NULL;
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| 181 | top = t->root;
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| 182 | while ((par = (*dpc)) != NULL) {
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| 183 | if (par->balance != 0) {
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| 184 | top = par;
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| 185 | }
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| 186 | gpa = par;
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[3bacee1] | 187 | dpc = par->key > key ? &par->lft : &par->rgt;
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[358ec13] | 188 | }
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| 189 |
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| 190 | /*
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[83a5cba] | 191 | * Initialize the new node.
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[358ec13] | 192 | */
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| 193 | newnode->key = key;
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| 194 | newnode->lft = NULL;
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| 195 | newnode->rgt = NULL;
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| 196 | newnode->par = gpa;
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| 197 | newnode->balance = 0;
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| 198 |
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| 199 | /*
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| 200 | * Insert first node into the empty tree.
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| 201 | */
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| 202 | if (t->root == NULL) {
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| 203 | *dpc = newnode;
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| 204 | return;
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| 205 | }
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| 206 |
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| 207 | /*
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[83a5cba] | 208 | * Insert the new node into the previously found leaf position.
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[358ec13] | 209 | */
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| 210 | *dpc = newnode;
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| 211 |
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| 212 | /*
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| 213 | * If the tree contains one node - end.
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| 214 | */
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| 215 | if (top == NULL)
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| 216 | return;
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| 217 |
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| 218 | /*
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| 219 | * Store pointer of top's father which points to the node with
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| 220 | * potentially broken balance (top).
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| 221 | */
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| 222 | if (top->par == NULL) {
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| 223 | dpc = &t->root;
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[1b20da0] | 224 | } else {
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[358ec13] | 225 | if (top->par->lft == top)
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| 226 | dpc = &top->par->lft;
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| 227 | else
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| 228 | dpc = &top->par->rgt;
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| 229 | }
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| 230 |
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| 231 | /*
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| 232 | * Repair all balances on the way from top node to the newly inserted
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| 233 | * node.
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| 234 | */
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| 235 | par = top;
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| 236 | while (par != newnode) {
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| 237 | if (par->key > key) {
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| 238 | par->balance--;
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| 239 | par = par->lft;
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| 240 | } else {
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| 241 | par->balance++;
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| 242 | par = par->rgt;
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| 243 | }
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| 244 | }
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[a35b458] | 245 |
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[358ec13] | 246 | /*
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| 247 | * To balance the tree, we must check and balance top node.
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| 248 | */
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| 249 | if (top->balance == -2) {
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| 250 | par = top->lft;
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| 251 | if (par->balance == -1) {
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| 252 | /*
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| 253 | * LL rotation.
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| 254 | */
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[83a5cba] | 255 | REBALANCE_INSERT_LL();
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[1b20da0] | 256 | } else {
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[358ec13] | 257 | /*
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| 258 | * LR rotation.
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| 259 | */
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[63e27ef] | 260 | assert(par->balance == 1);
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[a35b458] | 261 |
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[83a5cba] | 262 | REBALANCE_INSERT_LR();
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[358ec13] | 263 | }
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[1b20da0] | 264 | } else if (top->balance == 2) {
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[358ec13] | 265 | par = top->rgt;
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| 266 | if (par->balance == 1) {
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| 267 | /*
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| 268 | * RR rotation.
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| 269 | */
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[83a5cba] | 270 | REBALANCE_INSERT_RR();
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[358ec13] | 271 | } else {
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| 272 | /*
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| 273 | * RL rotation.
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| 274 | */
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[63e27ef] | 275 | assert(par->balance == -1);
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[a35b458] | 276 |
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[83a5cba] | 277 | REBALANCE_INSERT_RL();
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[358ec13] | 278 | }
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[1b20da0] | 279 | } else {
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[358ec13] | 280 | /*
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| 281 | * Balance is not broken, insertion is finised.
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| 282 | */
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| 283 | return;
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| 284 | }
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| 285 |
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| 286 | }
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| 287 |
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| 288 | /** Repair the tree after reparenting node u.
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| 289 | *
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| 290 | * If node u has no parent, mark it as the root of the whole tree. Otherwise
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| 291 | * node v represents stale address of one of the children of node u's parent.
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| 292 | * Replace v with w as node u parent's child (for most uses, u and w will be the
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| 293 | * same).
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| 294 | *
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| 295 | * @param t AVL tree.
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| 296 | * @param u Node whose new parent has a stale child pointer.
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| 297 | * @param v Stale child of node u's new parent.
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| 298 | * @param w New child of node u's new parent.
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| 299 | * @param dir If not NULL, address of the variable where to store information
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| 300 | * about whether w replaced v in the left or the right subtree of
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| 301 | * u's new parent.
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| 302 | * @param ro Read only operation; do not modify any tree pointers. This is
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| 303 | * useful for tracking direction via the dir pointer.
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[1b20da0] | 304 | *
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[358ec13] | 305 | * @return Zero if w became the new root of the tree, otherwise return
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| 306 | * non-zero.
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| 307 | */
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| 308 | static int
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[18b6a88] | 309 | repair(avltree_t *t, avltree_node_t *u, avltree_node_t *v, avltree_node_t *w,
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[358ec13] | 310 | int *dir, int ro)
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| 311 | {
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| 312 | if (u->par == NULL) {
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| 313 | if (!ro)
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[1b20da0] | 314 | t->root = w;
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[358ec13] | 315 | return 0;
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[1b20da0] | 316 | } else {
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[358ec13] | 317 | if (u->par->lft == v) {
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| 318 | if (!ro)
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| 319 | u->par->lft = w;
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| 320 | if (dir)
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| 321 | *dir = LEFT;
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| 322 | } else {
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[63e27ef] | 323 | assert(u->par->rgt == v);
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[358ec13] | 324 | if (!ro)
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| 325 | u->par->rgt = w;
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| 326 | if (dir)
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| 327 | *dir = RIGHT;
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| 328 | }
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| 329 | }
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| 330 | return 1;
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| 331 | }
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| 332 |
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[83a5cba] | 333 | #define REBALANCE_DELETE(DIR1, DIR2, SIGN) \
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[358ec13] | 334 | if (cur->balance == -1 * SIGN) { \
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| 335 | par->balance = 0; \
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| 336 | gpa->balance = 1 * SIGN; \
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| 337 | if (gpa->DIR1) \
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| 338 | gpa->DIR1->par = gpa; \
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| 339 | par->DIR2->par = par; \
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| 340 | } else if (cur->balance == 0) { \
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| 341 | par->balance = 0; \
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| 342 | gpa->balance = 0; \
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| 343 | if (gpa->DIR1) \
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| 344 | gpa->DIR1->par = gpa; \
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| 345 | if (par->DIR2) \
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| 346 | par->DIR2->par = par; \
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| 347 | } else { \
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| 348 | par->balance = -1 * SIGN; \
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| 349 | gpa->balance = 0; \
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| 350 | if (par->DIR2) \
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| 351 | par->DIR2->par = par; \
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| 352 | gpa->DIR1->par = gpa; \
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| 353 | } \
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| 354 | cur->balance = 0;
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| 355 |
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[83a5cba] | 356 | #define REBALANCE_DELETE_LR() REBALANCE_DELETE(lft, rgt, 1)
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| 357 | #define REBALANCE_DELETE_RL() REBALANCE_DELETE(rgt, lft, -1)
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[358ec13] | 358 |
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| 359 | /** Delete a node from the AVL tree.
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| 360 | *
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| 361 | * Because multiple identical keys are allowed, the parent pointers are
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| 362 | * essential during deletion.
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[1b20da0] | 363 | *
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[358ec13] | 364 | * @param t AVL tree structure.
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| 365 | * @param node Address of the node which will be deleted.
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| 366 | */
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| 367 | void avltree_delete(avltree_t *t, avltree_node_t *node)
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| 368 | {
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| 369 | avltree_node_t *cur;
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| 370 | avltree_node_t *par;
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| 371 | avltree_node_t *gpa;
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| 372 | int dir;
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| 373 |
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[63e27ef] | 374 | assert(t);
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| 375 | assert(node);
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[a35b458] | 376 |
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[358ec13] | 377 | if (node->lft == NULL) {
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| 378 | if (node->rgt) {
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| 379 | /*
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[1b20da0] | 380 | * Replace the node with its only right son.
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[358ec13] | 381 | *
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| 382 | * Balance of the right son will be repaired in the
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| 383 | * balancing cycle.
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| 384 | */
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| 385 | cur = node->rgt;
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| 386 | cur->par = node->par;
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| 387 | gpa = cur;
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| 388 | dir = RIGHT;
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[1b20da0] | 389 | cur->balance = node->balance;
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[358ec13] | 390 | } else {
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| 391 | if (node->par == NULL) {
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| 392 | /*
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| 393 | * The tree has only one node - it will become
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| 394 | * an empty tree and the balancing can end.
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| 395 | */
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| 396 | t->root = NULL;
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| 397 | return;
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| 398 | }
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| 399 | /*
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| 400 | * The node has no child, it will be deleted with no
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| 401 | * substitution.
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| 402 | */
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| 403 | gpa = node->par;
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| 404 | cur = NULL;
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[3bacee1] | 405 | dir = (gpa->lft == node) ? LEFT : RIGHT;
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[358ec13] | 406 | }
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| 407 | } else {
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| 408 | /*
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| 409 | * The node has the left son. Find a node with the smallest key
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| 410 | * in the left subtree and replace the deleted node with that
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| 411 | * node.
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| 412 | */
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[84239b1] | 413 | cur = node->lft;
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| 414 | while (cur->rgt != NULL)
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| 415 | cur = cur->rgt;
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[358ec13] | 416 |
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| 417 | if (cur != node->lft) {
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| 418 | /*
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| 419 | * The rightmost node of the deleted node's left subtree
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| 420 | * was found. Replace the deleted node with this node.
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| 421 | * Cutting off of the found node has two cases that
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| 422 | * depend on its left son.
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[1b20da0] | 423 | */
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[358ec13] | 424 | if (cur->lft) {
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| 425 | /*
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| 426 | * The found node has a left son.
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| 427 | */
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| 428 | gpa = cur->lft;
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| 429 | gpa->par = cur->par;
|
---|
| 430 | dir = LEFT;
|
---|
[1b20da0] | 431 | gpa->balance = cur->balance;
|
---|
[358ec13] | 432 | } else {
|
---|
| 433 | dir = RIGHT;
|
---|
| 434 | gpa = cur->par;
|
---|
| 435 | }
|
---|
| 436 | cur->par->rgt = cur->lft;
|
---|
| 437 | cur->lft = node->lft;
|
---|
[1b20da0] | 438 | cur->lft->par = cur;
|
---|
| 439 | } else {
|
---|
[358ec13] | 440 | /*
|
---|
| 441 | * The left son of the node hasn't got a right son. The
|
---|
| 442 | * left son will take the deleted node's place.
|
---|
| 443 | */
|
---|
| 444 | dir = LEFT;
|
---|
[1b20da0] | 445 | gpa = cur;
|
---|
[358ec13] | 446 | }
|
---|
| 447 | if (node->rgt)
|
---|
[1b20da0] | 448 | node->rgt->par = cur;
|
---|
[358ec13] | 449 | cur->rgt = node->rgt;
|
---|
| 450 | cur->balance = node->balance;
|
---|
| 451 | cur->par = node->par;
|
---|
| 452 | }
|
---|
[a35b458] | 453 |
|
---|
[358ec13] | 454 | /*
|
---|
| 455 | * Repair the parent node's pointer which pointed previously to the
|
---|
| 456 | * deleted node.
|
---|
| 457 | */
|
---|
| 458 | (void) repair(t, node, node, cur, NULL, false);
|
---|
[a35b458] | 459 |
|
---|
[358ec13] | 460 | /*
|
---|
| 461 | * Repair cycle which repairs balances of nodes on the way from from the
|
---|
| 462 | * cut-off node up to the root.
|
---|
| 463 | */
|
---|
[84239b1] | 464 | while (true) {
|
---|
[358ec13] | 465 | if (dir == LEFT) {
|
---|
| 466 | /*
|
---|
| 467 | * Deletion was made in the left subtree.
|
---|
| 468 | */
|
---|
| 469 | gpa->balance++;
|
---|
| 470 | if (gpa->balance == 1) {
|
---|
| 471 | /*
|
---|
| 472 | * Stop balancing, the tree is balanced.
|
---|
| 473 | */
|
---|
| 474 | break;
|
---|
[1b20da0] | 475 | } else if (gpa->balance == 2) {
|
---|
[358ec13] | 476 | /*
|
---|
| 477 | * Bad balance, heights of left and right
|
---|
| 478 | * subtrees differ more than by one.
|
---|
| 479 | */
|
---|
| 480 | par = gpa->rgt;
|
---|
| 481 |
|
---|
| 482 | if (par->balance == -1) {
|
---|
| 483 | /*
|
---|
| 484 | * RL rotation.
|
---|
| 485 | */
|
---|
[a35b458] | 486 |
|
---|
[358ec13] | 487 | cur = par->lft;
|
---|
| 488 | par->lft = cur->rgt;
|
---|
| 489 | cur->rgt = par;
|
---|
| 490 | gpa->rgt = cur->lft;
|
---|
| 491 | cur->lft = gpa;
|
---|
[a35b458] | 492 |
|
---|
[358ec13] | 493 | /*
|
---|
| 494 | * Repair balances and paternity of
|
---|
| 495 | * children, depending on the balance
|
---|
| 496 | * factor of the grand child (cur).
|
---|
| 497 | */
|
---|
[83a5cba] | 498 | REBALANCE_DELETE_RL();
|
---|
[a35b458] | 499 |
|
---|
[358ec13] | 500 | /*
|
---|
| 501 | * Repair paternity.
|
---|
| 502 | */
|
---|
| 503 | cur->par = gpa->par;
|
---|
| 504 | gpa->par = cur;
|
---|
| 505 | par->par = cur;
|
---|
| 506 |
|
---|
| 507 | if (!repair(t, cur, gpa, cur, &dir,
|
---|
| 508 | false))
|
---|
| 509 | break;
|
---|
| 510 | gpa = cur->par;
|
---|
| 511 | } else {
|
---|
| 512 | /*
|
---|
| 513 | * RR rotation.
|
---|
| 514 | */
|
---|
[a35b458] | 515 |
|
---|
[358ec13] | 516 | gpa->rgt = par->lft;
|
---|
| 517 | if (par->lft)
|
---|
| 518 | par->lft->par = gpa;
|
---|
| 519 | par->lft = gpa;
|
---|
[a35b458] | 520 |
|
---|
[358ec13] | 521 | /*
|
---|
| 522 | * Repair paternity.
|
---|
| 523 | */
|
---|
| 524 | par->par = gpa->par;
|
---|
| 525 | gpa->par = par;
|
---|
[a35b458] | 526 |
|
---|
[358ec13] | 527 | if (par->balance == 0) {
|
---|
| 528 | /*
|
---|
| 529 | * The right child of the
|
---|
| 530 | * balanced node is balanced,
|
---|
| 531 | * after RR rotation is done,
|
---|
| 532 | * the whole tree will be
|
---|
| 533 | * balanced.
|
---|
| 534 | */
|
---|
| 535 | par->balance = -1;
|
---|
| 536 | gpa->balance = 1;
|
---|
| 537 |
|
---|
| 538 | (void) repair(t, par, gpa, par,
|
---|
| 539 | NULL, false);
|
---|
[1b20da0] | 540 | break;
|
---|
[358ec13] | 541 | } else {
|
---|
| 542 | par->balance = 0;
|
---|
| 543 | gpa->balance = 0;
|
---|
| 544 | if (!repair(t, par, gpa, par,
|
---|
| 545 | &dir, false))
|
---|
| 546 | break;
|
---|
| 547 | }
|
---|
| 548 | gpa = par->par;
|
---|
| 549 | }
|
---|
| 550 | } else {
|
---|
| 551 | /*
|
---|
| 552 | * Repair the pointer which pointed to the
|
---|
| 553 | * balanced node. If it was root then balancing
|
---|
| 554 | * is finished else continue with the next
|
---|
| 555 | * iteration (parent node).
|
---|
| 556 | */
|
---|
| 557 | if (!repair(t, gpa, gpa, NULL, &dir, true))
|
---|
| 558 | break;
|
---|
| 559 | gpa = gpa->par;
|
---|
| 560 | }
|
---|
[1b20da0] | 561 | } else {
|
---|
[358ec13] | 562 | /*
|
---|
| 563 | * Deletion was made in the right subtree.
|
---|
| 564 | */
|
---|
| 565 | gpa->balance--;
|
---|
| 566 | if (gpa->balance == -1) {
|
---|
| 567 | /*
|
---|
| 568 | * Stop balancing, the tree is balanced.
|
---|
| 569 | */
|
---|
| 570 | break;
|
---|
| 571 | } else if (gpa->balance == -2) {
|
---|
| 572 | /*
|
---|
| 573 | * Bad balance, heights of left and right
|
---|
| 574 | * subtrees differ more than by one.
|
---|
| 575 | */
|
---|
| 576 | par = gpa->lft;
|
---|
[a35b458] | 577 |
|
---|
[358ec13] | 578 | if (par->balance == 1) {
|
---|
| 579 | /*
|
---|
| 580 | * LR rotation.
|
---|
| 581 | */
|
---|
[a35b458] | 582 |
|
---|
[358ec13] | 583 | cur = par->rgt;
|
---|
| 584 | par->rgt = cur->lft;
|
---|
| 585 | cur->lft = par;
|
---|
| 586 | gpa->lft = cur->rgt;
|
---|
| 587 | cur->rgt = gpa;
|
---|
[a35b458] | 588 |
|
---|
[358ec13] | 589 | /*
|
---|
| 590 | * Repair balances and paternity of
|
---|
| 591 | * children, depending on the balance
|
---|
| 592 | * factor of the grand child (cur).
|
---|
| 593 | */
|
---|
[83a5cba] | 594 | REBALANCE_DELETE_LR();
|
---|
[358ec13] | 595 |
|
---|
| 596 | /*
|
---|
| 597 | * Repair paternity.
|
---|
| 598 | */
|
---|
| 599 | cur->par = gpa->par;
|
---|
| 600 | gpa->par = cur;
|
---|
| 601 | par->par = cur;
|
---|
| 602 |
|
---|
| 603 | if (!repair(t, cur, gpa, cur, &dir,
|
---|
| 604 | false))
|
---|
| 605 | break;
|
---|
| 606 | gpa = cur->par;
|
---|
[1b20da0] | 607 | } else {
|
---|
[358ec13] | 608 | /*
|
---|
| 609 | * LL rotation.
|
---|
| 610 | */
|
---|
| 611 |
|
---|
| 612 | gpa->lft = par->rgt;
|
---|
| 613 | if (par->rgt)
|
---|
| 614 | par->rgt->par = gpa;
|
---|
| 615 | par->rgt = gpa;
|
---|
| 616 | /*
|
---|
| 617 | * Repair paternity.
|
---|
| 618 | */
|
---|
| 619 | par->par = gpa->par;
|
---|
| 620 | gpa->par = par;
|
---|
[a35b458] | 621 |
|
---|
[358ec13] | 622 | if (par->balance == 0) {
|
---|
| 623 | /*
|
---|
| 624 | * The left child of the
|
---|
| 625 | * balanced node is balanced,
|
---|
| 626 | * after LL rotation is done,
|
---|
| 627 | * the whole tree will be
|
---|
| 628 | * balanced.
|
---|
| 629 | */
|
---|
| 630 | par->balance = 1;
|
---|
| 631 | gpa->balance = -1;
|
---|
[a35b458] | 632 |
|
---|
[358ec13] | 633 | (void) repair(t, par, gpa, par,
|
---|
| 634 | NULL, false);
|
---|
| 635 | break;
|
---|
| 636 | } else {
|
---|
| 637 | par->balance = 0;
|
---|
| 638 | gpa->balance = 0;
|
---|
[a35b458] | 639 |
|
---|
[358ec13] | 640 | if (!repair(t, par, gpa, par,
|
---|
| 641 | &dir, false))
|
---|
| 642 | break;
|
---|
| 643 | }
|
---|
| 644 | gpa = par->par;
|
---|
| 645 | }
|
---|
| 646 | } else {
|
---|
| 647 | /*
|
---|
| 648 | * Repair the pointer which pointed to the
|
---|
| 649 | * balanced node. If it was root then balancing
|
---|
| 650 | * is finished. Otherwise continue with the next
|
---|
| 651 | * iteration (parent node).
|
---|
| 652 | */
|
---|
| 653 | if (!repair(t, gpa, gpa, NULL, &dir, true))
|
---|
| 654 | break;
|
---|
| 655 | gpa = gpa->par;
|
---|
| 656 | }
|
---|
| 657 | }
|
---|
| 658 | }
|
---|
| 659 | }
|
---|
| 660 |
|
---|
| 661 | /** Delete a node with the smallest key from the AVL tree.
|
---|
| 662 | *
|
---|
| 663 | * @param t AVL tree structure.
|
---|
| 664 | */
|
---|
| 665 | bool avltree_delete_min(avltree_t *t)
|
---|
| 666 | {
|
---|
| 667 | avltree_node_t *node;
|
---|
[a35b458] | 668 |
|
---|
[358ec13] | 669 | /*
|
---|
| 670 | * Start searching for the smallest key in the tree starting in the root
|
---|
| 671 | * node and continue in cycle to the leftmost node in the tree (which
|
---|
| 672 | * must have the smallest key).
|
---|
| 673 | */
|
---|
[a35b458] | 674 |
|
---|
[358ec13] | 675 | node = t->root;
|
---|
| 676 | if (!node)
|
---|
| 677 | return false;
|
---|
[a35b458] | 678 |
|
---|
[358ec13] | 679 | while (node->lft != NULL)
|
---|
| 680 | node = node->lft;
|
---|
[a35b458] | 681 |
|
---|
[1b20da0] | 682 | avltree_delete(t, node);
|
---|
[358ec13] | 683 |
|
---|
| 684 | return true;
|
---|
| 685 | }
|
---|
| 686 |
|
---|
[b76a2217] | 687 | /** Walk a subtree of an AVL tree in-order and apply a supplied walker on each
|
---|
| 688 | * visited node.
|
---|
| 689 | *
|
---|
| 690 | * @param node Node representing the root of an AVL subtree to be
|
---|
| 691 | * walked.
|
---|
| 692 | * @param walker Walker function that will be appliad on each visited
|
---|
| 693 | * node.
|
---|
| 694 | * @param arg Argument for the walker.
|
---|
| 695 | *
|
---|
| 696 | * @return Zero if the walk should stop or non-zero otherwise.
|
---|
| 697 | */
|
---|
| 698 | static bool _avltree_walk(avltree_node_t *node, avltree_walker_t walker,
|
---|
| 699 | void *arg)
|
---|
[d1e9321] | 700 | {
|
---|
[b76a2217] | 701 | if (node->lft) {
|
---|
| 702 | if (!_avltree_walk(node->lft, walker, arg))
|
---|
| 703 | return false;
|
---|
| 704 | }
|
---|
| 705 | if (!walker(node, arg))
|
---|
| 706 | return false;
|
---|
| 707 | if (node->rgt) {
|
---|
| 708 | if (!_avltree_walk(node->rgt, walker, arg))
|
---|
| 709 | return false;
|
---|
| 710 | }
|
---|
| 711 | return true;
|
---|
[d1e9321] | 712 | }
|
---|
| 713 |
|
---|
[b76a2217] | 714 | /** Walk the AVL tree in-order and apply the walker function on each visited
|
---|
| 715 | * node.
|
---|
[d1e9321] | 716 | *
|
---|
| 717 | * @param t AVL tree to be walked.
|
---|
| 718 | * @param walker Walker function that will be called on each visited
|
---|
| 719 | * node.
|
---|
[b76a2217] | 720 | * @param arg Argument for the walker.
|
---|
[d1e9321] | 721 | */
|
---|
[b76a2217] | 722 | void avltree_walk(avltree_t *t, avltree_walker_t walker, void *arg)
|
---|
[d1e9321] | 723 | {
|
---|
[7e36c8d] | 724 | if (t->root)
|
---|
| 725 | _avltree_walk(t->root, walker, arg);
|
---|
[d1e9321] | 726 | }
|
---|
| 727 |
|
---|
[358ec13] | 728 | /** @}
|
---|
| 729 | */
|
---|