Same Tree

leetcode 一道判断两棵树是否相同的题：

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.

直接写递归了，代码行数非常少

/**
 * Definition for binary tree
 * 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;
        if(p->val == q->val)return isSameTree(p->left, q->left) && isSameTree(p->right, q->right);
        else return false;
    }
};

也可以用队列对两棵二叉树层次遍历，在遍历的同时判断节点是否相同。