third_maximum_number.dart

/*

-* 414. Third Maximum Number *-

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.

 

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.
 

Constraints:

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

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


*/

class Solution {
  int thirdMax(List<int> nums) {
    Set<int> unique = Set<int>()..addAll(nums..sort((a, b) => a - b));
    if (unique.length < 3) {
      return unique.elementAt(unique.length - 3);
    }
    return unique.elementAt(unique.length - 3);
  }
}

void main() {
  final Solution sol = Solution();
  print(sol.thirdMax([2, 2, 3, 1]));
}