100. Same Tree

Description:

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.

解题思路：判断两棵树是否完全等价。可以直接用DPS的递归实现来判断。

/** * 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;        if((p==NULL&&q!=NULL)||(p!=NULL&q==NULL)) return false;        if(p->val==q->val){            return (isSameTree(p->left,q->left)&&isSameTree(p->right,q->right));        }        return false;    }};