LeetCode: 100. Same Tree

题目描述

Given two binary trees, write a function to check if they are the same or not.

Two binary trees are considered the same if they are structurally identical and the nodes have the same value.

Example 1:

Input:     1         1
          / \       / \          2   3     2   3

        [1,2,3],   [1,2,3]

Output: true

Example 2:

Input:     1         1
          /           \
         2             2

        [1,2],     [1,null,2]

Output: false

Example 3:

Input:     1         1
          / \       / \          2   1     1   2

        [1,2,1],   [1,1,2]

Output: false

解题思路 —— 递归求解

分别比较根节点，左子树和右子树是否相等。

AC 代码

/** * 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) {
        // 是否为空？
        if(p == nullptr || q == nullptr){
            return (p == nullptr && q == nullptr);
        }
        // 比较根节点，左子树和右子树
        return (p->val == q->val) && isSameTree(p->left, q->left) &&
            isSameTree(p->right, q->right);
    }
};