ArrayPartMinPairs.go

/*
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:
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].
*/

package main

import (
	"fmt"
	"sort"
)

func main() {
	input := []int{1,4,3,2}
	fmt.Println(arrayPairSum(input))
}

func arrayPairSum(nums []int) int {
	if nums == nil || len(nums) %2 != 0 {
		// nums must be non-nil and of even length
		return 0
	}

	sort.Ints(nums)

	tot := 0
	for i := 0; i < len(nums); i += 2 {
		tot += nums[i]
	}

	return tot
}