# 414. Third Maximum Number

## 1. Question

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

## 2. Examples

Example 1:

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


Example 2:

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


Example 3:

Input: nums = [2,2,3,1]
Output: 1
Explanation:
The first distinct maximum is 3.
The second distinct maximum is 2 (both 2's are counted together since they have the same value).
The third distinct maximum is 1.


## 3. Constraints

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

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

## 5. Solutions

class Solution {
public int thirdMax(int[] nums) {
TreeSet<Integer> set = new TreeSet<>();
for (int num : nums) {