LeetCode 100. Same Tree相同的树 (C++)
题目:
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
分析:
给定两个二叉树,判断他们是否相同,相同的二叉树拥有相同的结构,且节点的值也要相等。
递归求解。对于两个节点是否相同,有如下情况,当两个节点的左右节点均为空时返回true,如果两个节点,有一非空时,返回false,如果两个节点值不同时,返回false,之后递归求解节点的左右节点。
程序:
/** * 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 == nullptr && q == nullptr) return true; if(p == nullptr || q == nullptr) return false; if(p->val != q->val) return false; return isSameTree(p->left, q->left) && isSameTree(p->right, q->right); } };