561. Array Partition I

Problem:

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 = 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].

思路：

Solution (C++):

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;
}

性能：

Runtime: 116 ms  Memory Usage: 8.7 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB