---
description: 熟記 Set 的原生方法，size()、add()、has()、values()...
---

# # 217 Contains Duplicate

[題目連結在此](https://leetcode.com/problems/contains-duplicate/)    [ Set Method](https://ithelp.ithome.com.tw/articles/10214228)

```
Given an array of integers, find if the array contains any duplicates.

Your function should return true if any value appears at least twice in the array, 
and it should return false if every element is distinct.

input: 給一個整數的陣列 
output: 看這個陣列有沒有重覆的值
```

```
Example 1:

Input: [1,2,3,1]
Output: true
Example 2:

Input: [1,2,3,4]
Output: false
Example 3:

Input: [1,1,1,3,3,4,3,2,4,2]
Output: true
*/

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function(nums) {
  
};
```

### Edge Case

可能有負數或零

### 怎麼解

題目有提到 contains any duplicates，所以我會用 Set

* 去比較 Set.size 跟原來的 Array 長度一不一樣

```
var containsDuplicate = function(nums) {
  return new Set(nums).size < nums.length;
};
```

###
