LeetCode 100. Same Tree

100. Same Tree

Desctription
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.

Analysis
这道题所属的类目是DFS，题意是给出两个树，判断两棵树是否为同一棵树。
我的做法就是判断根的值是否相等以及左右子树是否相等。
注意空树的特殊情况。

Code

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