109 lines
2.5 KiB
C++
109 lines
2.5 KiB
C++
#include <iostream>
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#include <limits>
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using namespace std;
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struct TreeNode {
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int val;
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TreeNode *left;
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TreeNode *right;
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TreeNode(int x) : val(x), left(NULL), right(NULL) {}
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};
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// 插入节点
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TreeNode *insertNode(TreeNode *root, int val) {
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if (root == NULL) {
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return new TreeNode(val);
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}
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if (val < root->val) {
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root->left = insertNode(root->left, val);
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}
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else if (val > root->val) {
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root->right = insertNode(root->right, val);
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}
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return root;
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}
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// 删除节点
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TreeNode *deleteNode(TreeNode *root, int key) {
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if (root == NULL)
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return root;
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if (key < root->val) {
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root->left = deleteNode(root->left, key);
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}
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else if (key > root->val) {
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root->right = deleteNode(root->right, key);
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}
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else {
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if (root->left == NULL) {
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TreeNode *temp = root->right;
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delete root;
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return temp;
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}
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else if (root->right == NULL) {
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TreeNode *temp = root->left;
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delete root;
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return temp;
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}
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TreeNode *temp = root->right;
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while (temp && temp->left != NULL)
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temp = temp->left;
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root->val = temp->val;
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root->right = deleteNode(root->right, temp->val);
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}
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return root;
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}
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// 判断是否为二叉搜索树
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bool isValidBST(TreeNode *root, TreeNode *minNode = NULL, TreeNode *maxNode = NULL) {
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if (root == NULL)
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return true;
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if (minNode != NULL && root->val <= minNode->val || maxNode != NULL && root->val >= maxNode->val) {
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return false;
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}
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return isValidBST(root->left, minNode, root) && isValidBST(root->right, root, maxNode);
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}
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// 查找最大值和第二大值
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pair<int, int> findMaxAndSecondMax(TreeNode *root) {
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int maxVal = numeric_limits<int>::min();
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int secondMaxVal = numeric_limits<int>::min();
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TreeNode *curr = root;
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while (curr) {
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if (curr->val > maxVal) {
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secondMaxVal = maxVal;
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maxVal = curr->val;
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}
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else if (curr->val > secondMaxVal && curr->val < maxVal) {
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secondMaxVal = curr->val;
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}
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curr = curr->right;
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}
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return { maxVal, secondMaxVal };
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}
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// 主函数，用于测试以上所有功能
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int main() {
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int n;
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TreeNode *root = NULL;
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cout << "Enter a number to insert: ";
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while (true) {
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int val;
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cin >> val;
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if (val == -1)
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break;
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root = insertNode(root, val);
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}
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cout << "Is valid BST: " << (isValidBST(root) ? "Yes" : "No") << endl;
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auto maxAndSecondMax = findMaxAndSecondMax(root);
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cout << "Max: " << maxAndSecondMax.first << ", Second Max: " << maxAndSecondMax.second << endl;
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cout << "Enter a number to delete: ";
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cin >> n;
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root = deleteNode(root, n);
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cout << "After deleting " << n << ", is valid BST: " << (isValidBST(root) ? "Yes" : "No") << endl;
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return 0;
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} |