Same Tree -- leetcode

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.

基本思路：

进行递归操作，判断两个树是否相等。

1. 两树若都为空树，则相等。

2. 两树都不空；根结点的值相等；左子树相等；右子树相等。则该树相等。

在leetcode上实际执行时间为2ms。

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