100. 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.

两棵树的结构和值都要完全相同。

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