leetcode561 Array Partition I

 题目看不懂了 ，看了其余博客

class Solution {
public:
    int arrayPairSum(vector<int>& nums) {
        sort(nums.begin(),nums.end());
        int len = nums.length;
        int sum = 0;
        for(i=1;i<len;i+=2)
            sum += nums[i] 
        return sum;
    }
};