> For the complete documentation index, see [llms.txt](https://rock070.gitbook.io/leetcode-with-js/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://rock070.gitbook.io/leetcode-with-js/tree-shu/index-1.md).

# 100.same-tree

### **題目**

> Given the roots of two binary trees p and q, write a function to check if they are the same or not.

### **翻譯**

有兩個二元樹，請比較兩個是否結構、節點值皆相同

Example:

```js
    1       1 
   /  \    /  \
  2    3  2    3

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

```js
    1    1 
   /      \
  2        2

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

### **思路**

**一、極限值/特殊狀況**

* \[], \[0] => 是 false，因為第一個樹沒有節點，第二個樹只有一個節點。

**二、哪種資料結構解**

* Tree + DFS

**三、大概會怎麼解**

* 使用遞迴
* 判斷每個節點的是否相同

### **型別**

```js
/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} p
 * @param {TreeNode} q
 * @return {boolean}
 */
```

### **解題**

```js
var isSameTree = function(p, q) {
  if (!p && !q)  return true
  if (p?.val !== q?.val)  return false
  return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);
};
```