# LeetCode 414. Third Maximum Number

## Description

https://leetcode.com/problems/third-maximum-number/

Given integer array `nums`, return the third maximum number in this array. If the third maximum does not exist, return the maximum number.

Example 1:

```Input: nums = [3,2,1]
Output: 1
Explanation: The third maximum is 1.
```

Example 2:

```Input: nums = [1,2]
Output: 2
Explanation: The third maximum does not exist, so the maximum (2) is returned instead.
```

Example 3:

```Input: nums = [2,2,3,1]
Output: 1
Explanation: Note that the third maximum here means the third maximum distinct number.
Both numbers with value 2 are both considered as second maximum.
```

Constraints:

• `1 <= nums.length <= 104`
• `-231 <= nums[i] <= 231 - 1`

Follow up: Can you find an `O(n)` solution?

## Explanation

The easiest way is to sort and find the third largest.

## Python Solution

``````class Solution:
def thirdMax(self, nums: List[int]) -> int:

nums = list(set(nums))
nums = sorted(nums)

if len(nums) < 3:
return nums[-1]

return nums[-3]``````
• Time Complexity: O(log(N)).
• Space Complexity: O(N).