AVL樹的實現，

AVL樹的實現，

//avl_tree.h#include <stack>using std::stack;template <typename T>class AVL_TREE{public:AVL_TREE(){nil = new AVL_NODE(0, -1, NULL, NULL);tree_root = nil;}bool find(const T &val) const;void insert(const T &val);void del(const T &val);//惰性刪除typedef struct tagAVL_NODE{bool exist;T data;int height;struct tagAVL_NODE *left, *right;tagAVL_NODE(const T &val, int wg, tagAVL_NODE *cl, tagAVL_NODE *cr){data = val;height = wg;left = cl;right = cr;exist = 1;}}AVL_NODE;private:AVL_NODE* tree_root, * nil;AVL_NODE* own_insert(AVL_NODE* tree, const T &val);AVL_NODE* rolatewithleft(AVL_NODE *p);AVL_NODE* rolatewithright(AVL_NODE *p);};template <typename T> bool AVL_TREE<T>::find(const T &val) const{AVL_NODE *p = tree_root;while (p != nil && p->data != val){if (p->data < val)p = p->right;else if (p->data > val)p = p->left;}return p != nil && p->data == val && p->exist;}template <typename T> typename AVL_TREE<T>::AVL_NODE* AVL_TREE<T>::rolatewithleft(AVL_NODE *p){AVL_NODE *h = p->left;p->left = h->right;h->right = p;p->height = p->left->height > p->right->height ? p->left->height + 1 : p->right->height + 1;h->height = h->left->height > h->right->height ? h->left->height + 1 : h->right->height + 1;return h;}template <typename T> typename AVL_TREE<T>::AVL_NODE* AVL_TREE<T>::rolatewithright(AVL_NODE *p){AVL_NODE *h = p->right;p->right = h->left;h->left = p;p->height = p->left->height > p->right->height ? p->left->height + 1 : p->right->height + 1;h->height = h->left->height > h->right->height ? h->left->height + 1 : h->right->height + 1;return h;}template <typename T> void AVL_TREE<T>::insert(const T &val){AVL_NODE *p = own_insert(tree_root, val);if (tree_root == nil){tree_root = p;}else if (p->left == tree_root || p->right == tree_root)tree_root = p;}template <typename T> typename AVL_TREE<T>::AVL_NODE* AVL_TREE<T>::own_insert(AVL_NODE* tree, const T &val){if (nil == tree)tree = new AVL_NODE(val, 0, nil, nil);else if (val > tree->data){tree->right = own_insert(tree->right, val);if (2 == tree->right->height - tree->left->height){if (val > tree->right->data)tree = rolatewithright(tree);else{tree->right = rolatewithleft(tree->right);tree = rolatewithright(tree);}}}else if (val < tree->data){tree->left = own_insert(tree->left, val);if (2 == tree->left->height - tree->right->height){if (val < tree->right->data)tree = rolatewithleft(tree);else{tree->left = rolatewithright(tree->left);tree = rolatewithleft(tree);}}}else //val == tree->data{tree->exist = 1;}if (tree != nil) tree->height = (tree->right->height > tree->left->height ? tree->right->height : tree->left->height) + 1;return tree;}template <typename T> void AVL_TREE<T>::del(const T &val){AVL_NODE *p = tree_root;while (p != nil && p->data != val){if (p->data < val)p = p->right;else if (p->data > val)p = p->left;}if (p != nil && p->data == val)p->exist = 0;}