1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/glpavl.c Mon Dec 06 13:09:21 2010 +0100
1.3 @@ -0,0 +1,357 @@
1.4 +/* glpavl.c (binary search tree) */
1.5 +
1.6 +/***********************************************************************
1.7 +* This code is part of GLPK (GNU Linear Programming Kit).
1.8 +*
1.9 +* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
1.10 +* 2009, 2010 Andrew Makhorin, Department for Applied Informatics,
1.11 +* Moscow Aviation Institute, Moscow, Russia. All rights reserved.
1.12 +* E-mail: <mao@gnu.org>.
1.13 +*
1.14 +* GLPK is free software: you can redistribute it and/or modify it
1.15 +* under the terms of the GNU General Public License as published by
1.16 +* the Free Software Foundation, either version 3 of the License, or
1.17 +* (at your option) any later version.
1.18 +*
1.19 +* GLPK is distributed in the hope that it will be useful, but WITHOUT
1.20 +* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
1.21 +* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
1.22 +* License for more details.
1.23 +*
1.24 +* You should have received a copy of the GNU General Public License
1.25 +* along with GLPK. If not, see <http://www.gnu.org/licenses/>.
1.26 +***********************************************************************/
1.27 +
1.28 +#include "glpavl.h"
1.29 +
1.30 +AVL *avl_create_tree(int (*fcmp)(void *info, const void *key1,
1.31 + const void *key2), void *info)
1.32 +{ /* create AVL tree */
1.33 + AVL *tree;
1.34 + tree = xmalloc(sizeof(AVL));
1.35 + tree->pool = dmp_create_pool();
1.36 + tree->root = NULL;
1.37 + tree->fcmp = fcmp;
1.38 + tree->info = info;
1.39 + tree->size = 0;
1.40 + tree->height = 0;
1.41 + return tree;
1.42 +}
1.43 +
1.44 +int avl_strcmp(void *info, const void *key1, const void *key2)
1.45 +{ /* compare character string keys */
1.46 + xassert(info == info);
1.47 + return strcmp(key1, key2);
1.48 +}
1.49 +
1.50 +static AVLNODE *rotate_subtree(AVL *tree, AVLNODE *node);
1.51 +
1.52 +AVLNODE *avl_insert_node(AVL *tree, const void *key)
1.53 +{ /* insert new node into AVL tree */
1.54 + AVLNODE *p, *q, *r;
1.55 + short int flag;
1.56 + /* find an appropriate point for insertion */
1.57 + p = NULL; q = tree->root;
1.58 + while (q != NULL)
1.59 + { p = q;
1.60 + if (tree->fcmp(tree->info, key, p->key) <= 0)
1.61 + { flag = 0;
1.62 + q = p->left;
1.63 + p->rank++;
1.64 + }
1.65 + else
1.66 + { flag = 1;
1.67 + q = p->right;
1.68 + }
1.69 + }
1.70 + /* create new node and insert it into the tree */
1.71 + r = dmp_get_atom(tree->pool, sizeof(AVLNODE));
1.72 + r->key = key; r->type = 0; r->link = NULL;
1.73 + r->rank = 1; r->up = p;
1.74 + r->flag = (short int)(p == NULL ? 0 : flag);
1.75 + r->bal = 0; r->left = NULL; r->right = NULL;
1.76 + tree->size++;
1.77 + if (p == NULL)
1.78 + tree->root = r;
1.79 + else
1.80 + if (flag == 0) p->left = r; else p->right = r;
1.81 + /* go upstairs to the root and correct all subtrees affected by
1.82 + insertion */
1.83 + while (p != NULL)
1.84 + { if (flag == 0)
1.85 + { /* the height of the left subtree of [p] is increased */
1.86 + if (p->bal > 0)
1.87 + { p->bal = 0;
1.88 + break;
1.89 + }
1.90 + if (p->bal < 0)
1.91 + { rotate_subtree(tree, p);
1.92 + break;
1.93 + }
1.94 + p->bal = -1; flag = p->flag; p = p->up;
1.95 + }
1.96 + else
1.97 + { /* the height of the right subtree of [p] is increased */
1.98 + if (p->bal < 0)
1.99 + { p->bal = 0;
1.100 + break;
1.101 + }
1.102 + if (p->bal > 0)
1.103 + { rotate_subtree(tree, p);
1.104 + break;
1.105 + }
1.106 + p->bal = +1; flag = p->flag; p = p->up;
1.107 + }
1.108 + }
1.109 + /* if the root has been reached, the height of the entire tree is
1.110 + increased */
1.111 + if (p == NULL) tree->height++;
1.112 + return r;
1.113 +}
1.114 +
1.115 +void avl_set_node_type(AVLNODE *node, int type)
1.116 +{ /* assign the type field of specified node */
1.117 + node->type = type;
1.118 + return;
1.119 +}
1.120 +
1.121 +void avl_set_node_link(AVLNODE *node, void *link)
1.122 +{ /* assign the link field of specified node */
1.123 + node->link = link;
1.124 + return;
1.125 +}
1.126 +
1.127 +AVLNODE *avl_find_node(AVL *tree, const void *key)
1.128 +{ /* find node in AVL tree */
1.129 + AVLNODE *p;
1.130 + int c;
1.131 + p = tree->root;
1.132 + while (p != NULL)
1.133 + { c = tree->fcmp(tree->info, key, p->key);
1.134 + if (c == 0) break;
1.135 + p = (c < 0 ? p->left : p->right);
1.136 + }
1.137 + return p;
1.138 +}
1.139 +
1.140 +int avl_get_node_type(AVLNODE *node)
1.141 +{ /* retrieve the type field of specified node */
1.142 + return node->type;
1.143 +}
1.144 +
1.145 +void *avl_get_node_link(AVLNODE *node)
1.146 +{ /* retrieve the link field of specified node */
1.147 + return node->link;
1.148 +}
1.149 +
1.150 +static AVLNODE *find_next_node(AVL *tree, AVLNODE *node)
1.151 +{ /* find next node in AVL tree */
1.152 + AVLNODE *p, *q;
1.153 + if (tree->root == NULL) return NULL;
1.154 + p = node;
1.155 + q = (p == NULL ? tree->root : p->right);
1.156 + if (q == NULL)
1.157 + { /* go upstairs from the left subtree */
1.158 + for (;;)
1.159 + { q = p->up;
1.160 + if (q == NULL) break;
1.161 + if (p->flag == 0) break;
1.162 + p = q;
1.163 + }
1.164 + }
1.165 + else
1.166 + { /* go downstairs into the right subtree */
1.167 + for (;;)
1.168 + { p = q->left;
1.169 + if (p == NULL) break;
1.170 + q = p;
1.171 + }
1.172 + }
1.173 + return q;
1.174 +}
1.175 +
1.176 +void avl_delete_node(AVL *tree, AVLNODE *node)
1.177 +{ /* delete specified node from AVL tree */
1.178 + AVLNODE *f, *p, *q, *r, *s, *x, *y;
1.179 + short int flag;
1.180 + p = node;
1.181 + /* if both subtrees of the specified node are non-empty, the node
1.182 + should be interchanged with the next one, at least one subtree
1.183 + of which is always empty */
1.184 + if (p->left == NULL || p->right == NULL) goto skip;
1.185 + f = p->up; q = p->left;
1.186 + r = find_next_node(tree, p); s = r->right;
1.187 + if (p->right == r)
1.188 + { if (f == NULL)
1.189 + tree->root = r;
1.190 + else
1.191 + if (p->flag == 0) f->left = r; else f->right = r;
1.192 + r->rank = p->rank; r->up = f;
1.193 + r->flag = p->flag; r->bal = p->bal;
1.194 + r->left = q; r->right = p;
1.195 + q->up = r;
1.196 + p->rank = 1; p->up = r; p->flag = 1;
1.197 + p->bal = (short int)(s == NULL ? 0 : +1);
1.198 + p->left = NULL; p->right = s;
1.199 + if (s != NULL) s->up = p;
1.200 + }
1.201 + else
1.202 + { x = p->right; y = r->up;
1.203 + if (f == NULL)
1.204 + tree->root = r;
1.205 + else
1.206 + if (p->flag == 0) f->left = r; else f->right = r;
1.207 + r->rank = p->rank; r->up = f;
1.208 + r->flag = p->flag; r->bal = p->bal;
1.209 + r->left = q; r->right = x;
1.210 + q->up = r; x->up = r; y->left = p;
1.211 + p->rank = 1; p->up = y; p->flag = 0;
1.212 + p->bal = (short int)(s == NULL ? 0 : +1);
1.213 + p->left = NULL; p->right = s;
1.214 + if (s != NULL) s->up = p;
1.215 + }
1.216 +skip: /* now the specified node [p] has at least one empty subtree;
1.217 + go upstairs to the root and adjust the rank field of all nodes
1.218 + affected by deletion */
1.219 + q = p; f = q->up;
1.220 + while (f != NULL)
1.221 + { if (q->flag == 0) f->rank--;
1.222 + q = f; f = q->up;
1.223 + }
1.224 + /* delete the specified node from the tree */
1.225 + f = p->up; flag = p->flag;
1.226 + q = p->left != NULL ? p->left : p->right;
1.227 + if (f == NULL)
1.228 + tree->root = q;
1.229 + else
1.230 + if (flag == 0) f->left = q; else f->right = q;
1.231 + if (q != NULL) q->up = f, q->flag = flag;
1.232 + tree->size--;
1.233 + /* go upstairs to the root and correct all subtrees affected by
1.234 + deletion */
1.235 + while (f != NULL)
1.236 + { if (flag == 0)
1.237 + { /* the height of the left subtree of [f] is decreased */
1.238 + if (f->bal == 0)
1.239 + { f->bal = +1;
1.240 + break;
1.241 + }
1.242 + if (f->bal < 0)
1.243 + f->bal = 0;
1.244 + else
1.245 + { f = rotate_subtree(tree, f);
1.246 + if (f->bal < 0) break;
1.247 + }
1.248 + flag = f->flag; f = f->up;
1.249 + }
1.250 + else
1.251 + { /* the height of the right subtree of [f] is decreased */
1.252 + if (f->bal == 0)
1.253 + { f->bal = -1;
1.254 + break;
1.255 + }
1.256 + if (f->bal > 0)
1.257 + f->bal = 0;
1.258 + else
1.259 + { f = rotate_subtree(tree, f);
1.260 + if (f->bal > 0) break;
1.261 + }
1.262 + flag = f->flag; f = f->up;
1.263 + }
1.264 + }
1.265 + /* if the root has been reached, the height of the entire tree is
1.266 + decreased */
1.267 + if (f == NULL) tree->height--;
1.268 + /* returns the deleted node to the memory pool */
1.269 + dmp_free_atom(tree->pool, p, sizeof(AVLNODE));
1.270 + return;
1.271 +}
1.272 +
1.273 +static AVLNODE *rotate_subtree(AVL *tree, AVLNODE *node)
1.274 +{ /* restore balance of AVL subtree */
1.275 + AVLNODE *f, *p, *q, *r, *x, *y;
1.276 + xassert(node != NULL);
1.277 + p = node;
1.278 + if (p->bal < 0)
1.279 + { /* perform negative (left) rotation */
1.280 + f = p->up; q = p->left; r = q->right;
1.281 + if (q->bal <= 0)
1.282 + { /* perform single negative rotation */
1.283 + if (f == NULL)
1.284 + tree->root = q;
1.285 + else
1.286 + if (p->flag == 0) f->left = q; else f->right = q;
1.287 + p->rank -= q->rank;
1.288 + q->up = f; q->flag = p->flag; q->bal++; q->right = p;
1.289 + p->up = q; p->flag = 1;
1.290 + p->bal = (short int)(-q->bal); p->left = r;
1.291 + if (r != NULL) r->up = p, r->flag = 0;
1.292 + node = q;
1.293 + }
1.294 + else
1.295 + { /* perform double negative rotation */
1.296 + x = r->left; y = r->right;
1.297 + if (f == NULL)
1.298 + tree->root = r;
1.299 + else
1.300 + if (p->flag == 0) f->left = r; else f->right = r;
1.301 + p->rank -= (q->rank + r->rank);
1.302 + r->rank += q->rank;
1.303 + p->bal = (short int)(r->bal >= 0 ? 0 : +1);
1.304 + q->bal = (short int)(r->bal <= 0 ? 0 : -1);
1.305 + r->up = f; r->flag = p->flag; r->bal = 0;
1.306 + r->left = q; r->right = p;
1.307 + p->up = r; p->flag = 1; p->left = y;
1.308 + q->up = r; q->flag = 0; q->right = x;
1.309 + if (x != NULL) x->up = q, x->flag = 1;
1.310 + if (y != NULL) y->up = p, y->flag = 0;
1.311 + node = r;
1.312 + }
1.313 + }
1.314 + else
1.315 + { /* perform positive (right) rotation */
1.316 + f = p->up; q = p->right; r = q->left;
1.317 + if (q->bal >= 0)
1.318 + { /* perform single positive rotation */
1.319 + if (f == NULL)
1.320 + tree->root = q;
1.321 + else
1.322 + if (p->flag == 0) f->left = q; else f->right = q;
1.323 + q->rank += p->rank;
1.324 + q->up = f; q->flag = p->flag; q->bal--; q->left = p;
1.325 + p->up = q; p->flag = 0;
1.326 + p->bal = (short int)(-q->bal); p->right = r;
1.327 + if (r != NULL) r->up = p, r->flag = 1;
1.328 + node = q;
1.329 + }
1.330 + else
1.331 + { /* perform double positive rotation */
1.332 + x = r->left; y = r->right;
1.333 + if (f == NULL)
1.334 + tree->root = r;
1.335 + else
1.336 + if (p->flag == 0) f->left = r; else f->right = r;
1.337 + q->rank -= r->rank;
1.338 + r->rank += p->rank;
1.339 + p->bal = (short int)(r->bal <= 0 ? 0 : -1);
1.340 + q->bal = (short int)(r->bal >= 0 ? 0 : +1);
1.341 + r->up = f; r->flag = p->flag; r->bal = 0;
1.342 + r->left = p; r->right = q;
1.343 + p->up = r; p->flag = 0; p->right = x;
1.344 + q->up = r; q->flag = 1; q->left = y;
1.345 + if (x != NULL) x->up = p, x->flag = 1;
1.346 + if (y != NULL) y->up = q, y->flag = 0;
1.347 + node = r;
1.348 + }
1.349 + }
1.350 + return node;
1.351 +}
1.352 +
1.353 +void avl_delete_tree(AVL *tree)
1.354 +{ /* delete AVL tree */
1.355 + dmp_delete_pool(tree->pool);
1.356 + xfree(tree);
1.357 + return;
1.358 +}
1.359 +
1.360 +/* eof */