题目描述：
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:
n is a positive integer, which is in the range of [1, 10000].
All the integers in the array will be in the range of [-10000, 10000].
代码实现：
class Solution {
public:
int arrayPairSum(vector<int>& nums) {
int sum=0;
sort(nums.begin(),nums.end());
for(int i=0;i<nums.size();i+=2){
sum += nums[i];
}
return sum;
}
};