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.
分析：
题目要求判断两棵树是否相同，首先判断根节点是否相同，如果根节点相同，分别判断左、右子树是否相同。
代码如下：
/** * 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 false;}return isSameTree(p->left, q->left) && isSameTree(p->right ,q->right);}};
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