---
title: 'LeetCode 100. Same Tree'
disqus: hackmd
---

# LeetCode 100. Same Tree

## Description

Given the roots of two binary trees p and q, 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

Input: p = [1,2,3], q = [1,2,3]
Output: true

Input: p = [1,2], q = [1,null,2]
Output: false

## Constraints

The number of nodes in both trees is in the range [0, 100].
-10^4^ <= Node.val <= 10^4^

## Answer

此題可藉由遞迴方式實現，一開始先檢查到底NULL的情況，然後直接從return那邊就可以檢查val是否相等，再來就是兩樹往下推。

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */
 
 // 2022_05_02
bool isSameTree(struct TreeNode* p, struct TreeNode* q){
    if(p == NULL && q == NULL){return true;}
    else if(p == NULL || q == NULL){return false;}
    else{
        return (p->val == q->val) && isSameTree(p->left,q->left) && isSameTree(p->right,q->right);
    }
}

## Link
https://leetcode.com/problems/same-tree/
###### tags: `Leetcode`