第七周作业：Array Partition I

题面：

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]
题解：求分组后每组的最小值所加之和为最大。即可认为是将相邻最小两个数放入一组，即可联想到快排后，求各个奇数位的和。

代码：

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;
}
};