# Contains Duplicate

## Problem

Lets look at the question at hand

Given an integer array `nums`, return `true` if any value appears **at least twice** in the array, and return `false` if every element is distinct.

[Click Here](http://leetcode.com/problems/contains-duplicate/description/) to look at the question in detail.

## Approach

From the question it is clear that we are given an integer array `nums`, and we need to check if that array contains any duplicate values. In other words, we need to return `true` if there are duplicates and return `false` if there aren’t.

One of the data structures that will help when it comes to duplicate elements is `set`. In python, a set is a data structure that does not allow duplicate elements to be stored. hence all elements in a set are unique.

If you fire some neurons in your brain, you can easily make out where I’m going with this.

here’s what we’re gonna do,  
Let’s take the input nums and convert it into a set. Now all the duplicates are gone. Great! what now?  
Fire up those neurons a bit more and we have the answer.  
If there are duplicates, which would be removed, won’t the length of the data structure become smaller?  
Bazinga!

So here’s the final result,  
we take the length of the input array and comare it with a set of the input array. now we can return True if there are duplicates and return False if there aren’t.

## Solution

```python
class Solution:
    def containsDuplicate(self, nums: List[int]) -> bool:
        if len(nums) == len(set(nums)):
            return False

        else:
            return True
```

Well, that’s kind of it, really.

Pretty simple.