https://leetcode.com/problems/same-tree/
题目：
Given two binary trees, write a function to check if they are equal or not.
Two binary trees are considered equal if they are structurally identical and the nodes have the same value.
思路： DFS
AC代码：
1.递归
1 /** 2 * Definition for a binary tree node. 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool isSameTree(TreeNode* p, TreeNode* q) { 13 if (p==NULL && q==NULL) 14 return true; 15 else if(p!=NULL&&q!=NULL){ 16 bool ju; 17 if(p->val==q->val) 18 ju=true; 19 else 20 return false; 21 if (p->left==NULL && q->left==NULL) 22 ; 23 else if(p->left!=NULL && q->left!=NULL) 24 ju=ju&&isSameTree(p->left,q->left); 25 else 26 return false; 27 if (p->right==NULL && q->right==NULL) 28 ; 29 else if(p->right!=NULL && q->right!=NULL) 30 ju=ju&&isSameTree(p->right,q->right); 31 else 32 return false; 33 return ju; 34 } 35 else 36 return false; 37 } 38 };
2.非递归
1 /** 2 * Definition for a binary tree node. 3 * struct TreeNode { 4 * int val; 5 * TreeNode *left; 6 * TreeNode *right; 7 * TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8 * }; 9 */ 10 class Solution { 11 public: 12 bool isSameTree(TreeNode* p, TreeNode* q) { 13 if(p==NULL&&q==NULL) 14 return true; 15 else if(p!=NULL && q!=NULL){ 16 stack<TreeNode*> ms1,ms2; 17 ms1.push(p); 18 ms2.push(q); 19 TreeNode* p1,*q1; 20 while(!ms1.empty()){ 21 p1=ms1.top(); 22 q1=ms2.top(); 23 if(p1->val!=q1->val) 24 return false; 25 else{ 26 ms1.pop(); 27 ms2.pop(); 28 if(p1->right==NULL&&q1->right==NULL) 29 ; 30 else if(p1->right!=NULL&&q1->right!=NULL){ 31 ms1.push(p1->right); 32 ms2.push(q1->right); 33 } 34 else 35 return false; 36 if(p1->left==NULL&&q1->left==NULL) 37 ; 38 else if(p1->left!=NULL&&q1->left!=NULL){ 39 ms1.push(p1->left); 40 ms2.push(q1->left); 41 } 42 else 43 return false; 44 } 45 } 46 return true; 47 } 48 else 49 return false; 50 } 51 };