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| 1 | +/* 二叉查找树 - 数据结构 |
| 2 | + * Binary Search Tree - Data Structure |
| 3 | + * |
| 4 | + * 该二叉查找树的实现不存储重复元素。 |
| 5 | + */ |
| 6 | + |
| 7 | +#include "bst.hpp" |
| 8 | + |
| 9 | +/* 二叉查找树初始化 |
| 10 | + * 初始化为空树 |
| 11 | + */ |
| 12 | +BSTree::BSTree(void) |
| 13 | +{ |
| 14 | + this->root = NULL; |
| 15 | + return; |
| 16 | +} |
| 17 | + |
| 18 | +/* 二叉查找树初始化 |
| 19 | + * 根据给定值初始化根节点 |
| 20 | + */ |
| 21 | +BSTree::BSTree(const ValueType key) |
| 22 | +{ |
| 23 | + this->root = new BSTreeNode(key); |
| 24 | + return; |
| 25 | +} |
| 26 | + |
| 27 | +/* 二叉查找树销毁 |
| 28 | + * 递归销毁子树及其存储值并释放其内存 |
| 29 | + */ |
| 30 | +BSTree::~BSTree(void) |
| 31 | +{ |
| 32 | + if (root != NULL) delete this->root; |
| 33 | + return; |
| 34 | +} |
| 35 | + |
| 36 | +/* 二叉查找树查找 |
| 37 | + * 在该二叉查找树中查找是否存在指定值的元素 |
| 38 | + * 存在则返回对应二叉查找树节点指针,否则返回NULL |
| 39 | + */ |
| 40 | +BSTreeNode *BSTree::Find(const ValueType key) |
| 41 | +{ |
| 42 | + BSTreeNode *node = this->root; |
| 43 | + |
| 44 | + while (node != NULL && node->value != key) { |
| 45 | + node = key < node->value ? node->left : node->right; |
| 46 | + } |
| 47 | + return node; |
| 48 | +} |
| 49 | + |
| 50 | +/* 二叉查找树查找最小元素值 |
| 51 | + * 在该二叉查找树中查找出存储最小元素的节点并返回其指针 |
| 52 | + */ |
| 53 | +BSTreeNode *BSTree::FindMin(void) |
| 54 | +{ |
| 55 | + BSTreeNode *node = this->root; |
| 56 | + |
| 57 | + while (node != NULL && node->left != NULL) { |
| 58 | + node = node->left; |
| 59 | + } |
| 60 | + return node; |
| 61 | +} |
| 62 | + |
| 63 | +/* 二叉查找树查找最大元素值 |
| 64 | + * 在该二叉查找树中查找出最大元素值并返回 |
| 65 | + */ |
| 66 | +BSTreeNode *BSTree::FindMax(void) |
| 67 | +{ |
| 68 | + BSTreeNode *node = this->root; |
| 69 | + |
| 70 | + while (node != NULL && node->right != NULL) { |
| 71 | + node = node->right; |
| 72 | + } |
| 73 | + return node; |
| 74 | +} |
| 75 | + |
| 76 | +/* 二叉查找树插入 |
| 77 | + * 在该二叉查找树中插入一个元素 |
| 78 | + * 如果该元素已经存在则不做操作 |
| 79 | + */ |
| 80 | +void BSTree::Insert(const ValueType key) |
| 81 | +{ |
| 82 | + if (this->root == NULL) { |
| 83 | + this->root = new BSTreeNode(key); |
| 84 | + return; |
| 85 | + } |
| 86 | + |
| 87 | + BSTreeNode *node = this->root; |
| 88 | + |
| 89 | + while (node->value != key) { |
| 90 | + if (key < node->value) { |
| 91 | + node = node->left == NULL ? new BSTreeNode(key) : node->left; |
| 92 | + } else { |
| 93 | + node = node->right == NULL ? new BSTreeNode(key) : node->right; |
| 94 | + } |
| 95 | + } |
| 96 | + return; |
| 97 | +} |
| 98 | + |
| 99 | +/* 二叉查找树删除 |
| 100 | + * 在该二叉查找树中删除元素 |
| 101 | + * 如果不存在对应元素则不删除任何元素直接返回 |
| 102 | + */ |
| 103 | +void BSTree::Delete(const ValueType key) |
| 104 | +{ |
| 105 | + if (this->root != NULL) this->root = this->root->Delete(key); |
| 106 | + return; |
| 107 | +} |
| 108 | + |
| 109 | +/* 二叉查找树节点初始化 |
| 110 | + * 存储值设置为给定值 |
| 111 | + */ |
| 112 | +BSTreeNode::BSTreeNode(const ValueType key) |
| 113 | +{ |
| 114 | + this->value = key; |
| 115 | + this->left = NULL; |
| 116 | + this->right = NULL; |
| 117 | + return; |
| 118 | +} |
| 119 | + |
| 120 | +/* 二叉查找树节点销毁 |
| 121 | + * 将会递归销毁子树并释放内存 |
| 122 | + */ |
| 123 | +BSTreeNode::~BSTreeNode(void) |
| 124 | +{ |
| 125 | + if (this->left != NULL) delete this->left; |
| 126 | + if (this->right != NULL) delete this->right; |
| 127 | + return; |
| 128 | +} |
| 129 | + |
| 130 | +/* 二叉查找树节点删除 |
| 131 | + * 在以该二叉查找树节点为根节点的树中删除元素 |
| 132 | + * 返回删除元素后的新二叉查找树根节点指针 |
| 133 | + * 没有待删除元素则不做操作直接返回自身 |
| 134 | + */ |
| 135 | +BSTreeNode *BSTreeNode::Delete(const ValueType key) |
| 136 | +{ |
| 137 | + // 待删除节点不是自己 |
| 138 | + if (key < this->value) { |
| 139 | + if (this->left != NULL) { |
| 140 | + this->left = this->left->Delete(key); |
| 141 | + } |
| 142 | + return this; |
| 143 | + } |
| 144 | + if (key > this->value) { |
| 145 | + if (this->right != NULL) { |
| 146 | + this->right = this->right->Delete(key); |
| 147 | + } |
| 148 | + return this; |
| 149 | + } |
| 150 | + |
| 151 | + // 待删除节点是自己 |
| 152 | + |
| 153 | + // 待删除节点左右子树都不为空 |
| 154 | + if (this->left != NULL && this->right != NULL) { |
| 155 | + // 查找右子树最小元素节点 |
| 156 | + BSTreeNode *min_node = this->right; |
| 157 | + while (min_node->left != NULL) { |
| 158 | + min_node = min_node->left; |
| 159 | + } |
| 160 | + // 更新与删除 |
| 161 | + this->value = min_node->value; |
| 162 | + this->right = this->right->Delete(min_node->value); |
| 163 | + return this; |
| 164 | + } |
| 165 | + |
| 166 | + // 待删除节点为叶子节点 |
| 167 | + if (this->left == NULL && this->right == NULL) { |
| 168 | + delete this; |
| 169 | + return NULL; |
| 170 | + } |
| 171 | + |
| 172 | + // 待删除节点仅有一颗子树 |
| 173 | + BSTreeNode *tmp = this->left == NULL ? this->right : this->left; |
| 174 | + delete this; |
| 175 | + return tmp; |
| 176 | +} |
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