Same Tree问题及解法

问题描述：

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.

问题分析：

判断两棵树是不是相等，主要看以下几个方面

1.树顶点是否值相同

2.左子树是否相同

3.右子树是否相同

用以上三个条件进行DFS遍历即可求的答案。

过程详见代码：

/**
* Definition for a binary tree node.
* 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) {
if(p == NULL && q == NULL) return true;
else if(p == NULL) return false;
else if(q == NULL) return false;

if(p->val == q->val)
{
return isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
}
else return false;
}
};