最近因为要给ccache加入红黑树的支持, 找出来曾经实现的代码作为参考, 这才发现原来 的实现都是有问题的,也怪我的测试用例写的不好, 仅仅对插入操作进行了测试, 我向所有因 为阅读了这份代码而造成困惑的朋友表示道歉.
这次重新实现, 所有的代码推倒重新编写, 参考了linux内核中红黑树的实现算法, 并且 对测试用例进行了加强,希望这是最后一个对红黑树算法的修订版本.
/*----------------------------------------------------------- RB-Tree的插入和删除操作的实现算法 参考资料: 1) <<Introduction to algorithm>> 2) http://lxr.linux.no/linux/lib/rbtree.c 作者：http://www.cppblog.com/converse/ 您可以自由的传播，修改这份代码，转载处请注明原作者 红黑树的几个性质: 1) 每个结点只有红和黑两种颜色 2) 根结点是黑色的 3)空节点是黑色的（红黑树中，根节点的parent以及所有叶节点lchild、rchild都不指向NULL，而是指向一个定义好的空节点）。 4) 如果一个结点是红色的,那么它的左右两个子结点的颜色是黑色的 5) 对于每个结点而言,从这个结点到叶子结点的任何路径上的黑色结点 的数目相同-------------------------------------------------------------*/#include <stdio.h>#include <stdlib.h>#include <string.h>typedef int key_t;typedef int data_t;typedef enum color_t{ RED = 0, BLACK = 1}color_t;typedef struct rb_node_t{ struct rb_node_t *left, *right, *parent; key_t key; data_t data; color_t color;}rb_node_t;/* forward declaration */rb_node_t* rb_insert(key_t key, data_t data, rb_node_t* root);rb_node_t* rb_search(key_t key, rb_node_t* root);rb_node_t* rb_erase(key_t key, rb_node_t* root);int main(){ int i, count = 900000; key_t key; rb_node_t* root = NULL, *node = NULL; srand(time(NULL)); for (i = 1; i < count; ++i) { key = rand() % count; if ((root = rb_insert(key, i, root))) { printf("[i = %d] insert key %d success!\n", i, key); } else { printf("[i = %d] insert key %d error!\n", i, key); exit(-1); } if ((node = rb_search(key, root))) { printf("[i = %d] search key %d success!\n", i, key); } else { printf("[i = %d] search key %d error!\n", i, key); exit(-1); } if (!(i % 10)) { if ((root = rb_erase(key, root))) { printf("[i = %d] erase key %d success\n", i, key); } else { printf("[i = %d] erase key %d error\n", i, key); } } } return 0;}static rb_node_t* rb_new_node(key_t key, data_t data){ rb_node_t *node = (rb_node_t*)malloc(sizeof(struct rb_node_t)); if (!node) { printf("malloc error!\n"); exit(-1); } node->key = key, node->data = data; return node;}/*-----------------------------------------------------------| node right| / \ ==> / \| a right node y| / \ / \| b y a b -----------------------------------------------------------*/static rb_node_t* rb_rotate_left(rb_node_t* node, rb_node_t* root){ rb_node_t* right = node->right; if ((node->right = right->left)) { right->left->parent = node; } right->left = node; if ((right->parent = node->parent)) { if (node == node->parent->right) { node->parent->right = right; } else { node->parent->left = right; } } else { root = right; } node->parent = right; return root;}/*-----------------------------------------------------------| node left| / \ / \| left y ==> a node| / \ / \| a b b y-----------------------------------------------------------*/static rb_node_t* rb_rotate_right(rb_node_t* node, rb_node_t* root){ rb_node_t* left = node->left; if ((node->left = left->right)) { left->right->parent = node; } left->right = node; if ((left->parent = node->parent)) { if (node == node->parent->right) { node->parent->right = left; } else { node->parent->left = left; } } else { root = left; } node->parent = left; return root;}static rb_node_t* rb_insert_rebalance(rb_node_t *node, rb_node_t *root){ rb_node_t *parent, *gparent, *uncle, *tmp; while ((parent = node->parent) && parent->color == RED) { gparent = parent->parent; if (parent == gparent->left) { uncle = gparent->right; if (uncle && uncle->color == RED) { uncle->color = BLACK; parent->color = BLACK; gparent->color = RED; node = gparent; } else { if (parent->right == node) { root = rb_rotate_left(parent, root); tmp = parent; parent = node; node = tmp; } parent->color = BLACK; gparent->color = RED; root = rb_rotate_right(gparent, root); } } else { uncle = gparent->left; if (uncle && uncle->color == RED) { uncle->color = BLACK; parent->color = BLACK; gparent->color = RED; node = gparent; } else { if (parent->left == node) { root = rb_rotate_right(parent, root); tmp = parent; parent = node; node = tmp; } parent->color = BLACK; gparent->color = RED; root = rb_rotate_left(gparent, root); } } } root->color = BLACK; return root;}static rb_node_t* rb_erase_rebalance(rb_node_t *node, rb_node_t *parent, rb_node_t *root){ rb_node_t *other, *o_left, *o_right; while ((!node || node->color == BLACK) && node != root) { if (parent->left == node) { other = parent->right; if (other->color == RED) { other->color = BLACK; parent->color = RED; root = rb_rotate_left(parent, root); other = parent->right; } if ((!other->left || other->left->color == BLACK) && (!other->right || other->right->color == BLACK)) { other->color = RED; node = parent; parent = node->parent; } else { if (!other->right || other->right->color == BLACK) { if ((o_left = other->left)) { o_left->color = BLACK; } other->color = RED; root = rb_rotate_right(other, root); other = parent->right; } other->color = parent->color; parent->color = BLACK; if (other->right) { other->right->color = BLACK; } root = rb_rotate_left(parent, root); node = root; break; } } else { other = parent->left; if (other->color == RED) { other->color = BLACK; parent->color = RED; root = rb_rotate_right(parent, root); other = parent->left; } if ((!other->left || other->left->color == BLACK) && (!other->right || other->right->color == BLACK)) { other->color = RED; node = parent; parent = node->parent; } else { if (!other->left || other->left->color == BLACK) { if ((o_right = other->right)) { o_right->color = BLACK; } other->color = RED; root = rb_rotate_left(other, root); other = parent->left; } other->color = parent->color; parent->color = BLACK; if (other->left) { other->left->color = BLACK; } root = rb_rotate_right(parent, root); node = root; break; } } } if (node) { node->color = BLACK; } return root;}static rb_node_t* rb_search_auxiliary(key_t key, rb_node_t* root, rb_node_t** save){ rb_node_t *node = root, *parent = NULL; int ret; while (node) { parent = node; ret = node->key - key; if (0 < ret) { node = node->left; } else if (0 > ret) { node = node->right; } else { return node; } } if (save) { *save = parent; } return NULL;}rb_node_t* rb_insert(key_t key, data_t data, rb_node_t* root){ rb_node_t *parent = NULL, *node; parent = NULL; if ((node = rb_search_auxiliary(key, root, &parent))) { return root; } node = rb_new_node(key, data); node->parent = parent; node->left = node->right = NULL; node->color = RED; if (parent) { if (parent->key > key) { parent->left = node; } else { parent->right = node; } } else { root = node; } return rb_insert_rebalance(node, root);}rb_node_t* rb_search(key_t key, rb_node_t* root){ return rb_search_auxiliary(key, root, NULL);}rb_node_t* rb_erase(key_t key, rb_node_t *root){ rb_node_t *child, *parent, *old, *left, *node; color_t color; if (!(node = rb_search_auxiliary(key, root, NULL))) { printf("key %d is not exist!\n"); return root; } old = node; if (node->left && node->right) { node = node->right; while ((left = node->left) != NULL) { node = left; } child = node->right; parent = node->parent; color = node->color; if (child) { child->parent = parent; } if (parent) { if (parent->left == node) { parent->left = child; } else { parent->right = child; } } else { root = child; } if (node->parent == old) { parent = node; } node->parent = old->parent; node->color = old->color; node->right = old->right; node->left = old->left; if (old->parent) { if (old->parent->left == old) { old->parent->left = node; } else { old->parent->right = node; } } else { root = node; } old->left->parent = node; if (old->right) { old->right->parent = node; } } else { if (!node->left) { child = node->right; } else if (!node->right) { child = node->left; } parent = node->parent; color = node->color; if (child) { child->parent = parent; } if (parent) { if (parent->left == node) { parent->left = child; } else { parent->right = child; } } else { root = child; } } free(old); if (color == BLACK) { root = rb_erase_rebalance(child, parent, root); } return root;}
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时间： 2024-10-31 16:24:16