LeetCode——561. Array Partition I（贪心，C++）

题目链接

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: 4Explanation: n is 2, and the maximum sum of pairs is 4 = min(1, 2) + min(3, 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].

题解：

       假设从数列中取出的数为A1-An/2，那么肯定存在一组数B1-Bn/2，不难想象，要使得结果最大，那么Ai的最佳取法即为顺序排列中的奇数位。

代码：

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