> For the complete documentation index, see [llms.txt](https://timmybeeflin.gitbook.io/cracking-leetcode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://timmybeeflin.gitbook.io/cracking-leetcode/tree/100.-same-tree.md).

# 100. Same Tree

<https://leetcode.com/problems/same-tree/>

O(n)

O(n)

```java
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if (p == null && q == null) {
            return true;
        }
        // means (p == null && q != null) || (p != null && q == null)
        // so if (p == null && q == null) { should put first
        // then we can just write p == null || q == null here
        if (p == null || q == null) { 
            return false;
        }
        return p.val == q.val && isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
    }
}
```