561. Array Partition I（LeetCode）

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.

Example 1:

Input: [1,4,3,2]

Output: 4
Explanation: n is 2, and the maximum sum of pairs is 4.

Note:

1. n is a positive integer, which is in the range of [1, 10000].
2. All the integers in the array will be in the range of [-10000, 10000].

   #include<iostream>
   #include<vector>
   #include<algorithm>
   using namespace std;
   class Solution {
   public:
       int arrayPairSum(vector<int>& nums) {
           sort(nums.begin(), nums.end());
           int n = nums.size();
           int sum = 0;
           for (int i = 0; i < n; i += 2)
           {
               sum += nums[i];
           }
           return sum;
       }
   };
   int main()
   {
       vector<int> num{ 1, 4, 3, 2 };
       Solution s;
       cout << s.arrayPairSum(num) << endl;
       system("pause");
       return 0;
   }