---
title: "LeetCode #217: Contains Duplicate"
url: https://perrotta.dev/2025/12/leetcode-%23217-contains-duplicate/
last_updated: 2026-01-06
---


[LeetCode #217: Contains Duplicate](https://leetcode.com/problems/contains-duplicate):

With `Counter()`:

```python
from collections import Counter

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        return len([x for x in Counter(nums).values() if x >= 2]) > 0
```

OR a small variant with `any`:

```python
from collections import Counter

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        return any(x >= 2 for x in Counter(nums).values())
```

OR:

```python
from collections import Counter

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        if not nums:
            return False

        return Counter(nums).most_common()[0][1] >= 2
```

OR with `set()`:

```python
from collections import Counter

class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        s = set()
        for num in nums:
            if num in s:
                return True
            s.add(num)
        return False
```