561、Array Partition

Given an array of 2n integers, your task is to group these integers into n pairs of integer, say (a1, b1), (a2, b2), ..., (an, bn) which makes sum of min(ai, bi) for all i from 1 to n as large as possible.

public int arrayPairSum(int[] nums) {
  Arrays.sort(nums);
  int sum=0;
  for (int i=0;i<nums.length;i+=2){
    sum+=nums[i];
  }
  return sum;
}