[LeetCode] Same Tree

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.

用树的遍历来检查。

 1 /**
 2  * Definition for binary tree
 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         // Start typing your C/C++ solution below
14         // DO NOT write int main() function
15         if (p == NULL && q == NULL)
16             return true;
17             
18         if (p == NULL || q == NULL)
19             return false;
20             
21         bool leftSame = isSameTree(p->left, q->left);
22         bool rightSame = isSameTree(p->right, q->right);
23         
24         return leftSame && rightSame && p->val == q->val;                 
25     }
26 };