邪灵天使

摘要： class Solution {public: int numDecodings(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function if(s==""||s[0]=='0') return 0; int count = s.length(); int pre = 1; int cur = 1; int code; for(int i = ... 阅读全文

摘要： class Solution {public: bool isValid(string s) { // Start typing your C/C++ solution below // DO NOT write int main() function stack mystack; int count = s.length(); for(int i = 0;i < count;i++) { if(s[i]=='('||s[i]=='{'||s[i]=='[') ... 阅读全文

摘要： class Solution {public: vector > generate(int numRows) { // Start typing your C/C++ solution below // DO NOT write int main() function vector pre; vector temp; vector >result; if(numRows<=0) return result; temp.push_back(1); result.pu... 阅读全文

摘要： 后序与中序得原二叉树，与上篇类似。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: TreeNode *buildTree(vector &inorder, vector &postorder) { // Start typ... 阅读全文

摘要： 已知前序遍历和中序遍历可以得到原二叉树。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: TreeNode *buildTree(vector &preorder, vector &inorder) { // Start t... 阅读全文

摘要： 题目的意思是z字形遍历二叉树，代码有点冗余希望大牛么赐教，大概意思是要不从左到右遍历存入栈中，要不从右至左存入栈中，为了统一操作新建了一个类似头节点的树节点。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: vector > zigzag... 阅读全文

摘要： 题目意思为一个二叉搜索树，有两个元素位置颠倒了，现在让你把它还原，但是题目要求空间复杂度O(1)，我们知道二叉搜索树的中序遍历是有序的，那么利用这一点，找到第一个无序的地方，记录为first,第二个为second，这样就是常量空间复杂度了，注意有一种情况是刚好两个相邻的颠倒顺序。/** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), rig... 阅读全文

摘要： /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {private: vector inorder; public: bool isValidBST(TreeNode *root) { // Start typing your C/C+... 阅读全文

摘要： /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: bool isSameTree(TreeNode *p, TreeNode *q) { // Start typing your C/C++ solution below ... 阅读全文

摘要： /** * Definition for binary tree * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; * TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public: bool isSymmetric(TreeNode *root) { // Start typing your C/C++ solution below // ... 阅读全文