Given an integer array nums of 2n integers, group these integers into n pairs (a1, b1),
(a2, b2), ..., (an, bn) such that the sum of min(ai, bi) for all i is maximized.
Return the maximized sum.

Input: nums = [1,4,3,2]
Output: 4
Explanation: All possible pairings (ignoring the ordering of elements) are:

1. (1, 4), (2, 3) -> min(1, 4) + min(2, 3) = 1 + 2 = 3
   
2. (1, 3), (2, 4) -> min(1, 3) + min(2, 4) = 1 + 2 = 3
   
3. (1, 2), (3, 4) -> min(1, 2) + min(3, 4) = 1 + 3 = 4
   So the maximum possible sum is 4.
   

Input: nums = [6,2,6,5,1,2]
Output: 9
Explanation: The optimal pairing is (2, 1), (2, 5), (6, 6).
min(2, 1) + min(2, 5) + min(6, 6) = 1 + 2 + 6 = 9.

1 <= n <= 104
nums.length == 2 * n
-104 <= nums[i] <= 104