LeetCode(100. Same Tree)题解.md

LeetCode(100. Same Tree)题解

---

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

Easy题，直接使用递归计算即可。首先比较根节点，然后比较左子树和右子树，只有都相同才能返回True，否则False。

代码如下：

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