text: // https://leetcode.com/problems/array-partition-i/
  
  // Sort, and add every other number
  
  class Solution {
  public:
      int arrayPairSum(vector<int>& nums) {
          sort(nums.begin(), nums.end());
          int sum = 0;
          for(int i = 0; i < nums.size(); i += 2)
              sum += nums[i];
          return sum;
      }
  };