> For the complete documentation index, see [llms.txt](https://jaywin.gitbook.io/leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jaywin.gitbook.io/leetcode/solutions/0100-same-tree.md).

# 0100. Same Tree

<https://leetcode.com/problems/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 1:**

![](https://assets.leetcode.com/uploads/2020/12/20/ex1.jpg)

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

**Example 2:**

![](https://assets.leetcode.com/uploads/2020/12/20/ex2.jpg)

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

**Example 3:**

![](https://assets.leetcode.com/uploads/2020/12/20/ex3.jpg)

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

**Constraints:**

* The number of nodes in both trees is in the range `[0, 100]`.
* `-104 <= Node.val <= 104`

## ac

```java
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        // exit
        if (p == null && q == null) return true;
        else if (p == null || q == null) return false;

        if (p.val != q.val) return false;

        return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
}
```