100

100. Same Tree (Easy)

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

Related Topics:
Tree, Depth-first Search

Solution 1.

// OJ: https://leetcode.com/problems/same-tree/
// Author: github.com/lzl124631x
// Time: O(N)
// Space: O(H)
class Solution {
public:
    bool isSameTree(TreeNode* p, TreeNode* q) {
        return (!p && !q) || (p && q && p->val == q->val && isSameTree(p->left, q->left) && isSameTree(p->right, q->right));
    }
};