Added TwoSum implemented in Go

Author: Mason Johnson

TwoSum/Go/twosum.go

@@ -0,0 +1,51 @@
+/*
+	TwoSum takes a target sum and any number of NON-REPEATING integers and returns
+	the two integers that add up to the target if they exist.
+	For example, with a target of 5, and the list of integers 1 2 3 4
+	the algorithm would return [2,3]
+*/
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	fmt.Printf("Input Target Sum: ")
+	var target int
+	fmt.Scan(&target)
+	fmt.Printf("Input Array of Integers: ")
+	var values []int
+	scanner := bufio.NewScanner(os.Stdin)
+	scanner.Scan()
+	values = numbers(scanner.Text())
+
+	fmt.Println(twoSum(values, target))
+}
+
+func twoSum(nums []int, target int) []int {
+	// key is complement, value is index
+	comps := make(map[int]int, len(nums))
+	for i, val := range nums {
+		if index, ok := comps[val]; ok {
+			return []int{nums[index], nums[i]}
+		}
+		comps[target-val] = i
+	}
+	return []int{}
+}
+
+func numbers(s string) []int {
+	var n []int
+	for _, f := range strings.Fields(s) {
+		i, err := strconv.Atoi(f)
+		if err == nil {
+			n = append(n, i)
+		}
+	}
+	return n
+}