isSumOf3.go

package main

import (
	"fmt"
	"sort"
)

// Implementation of sum of three ints. Do any three ints
// in the given slice sum up to the target?
// Interate through eacn int. For each iteration set low and
// high pointers for the elements to the right of the current
// element and adjust each pointer depending on whether the sum of
// the current element + left + right is less than or greater than
// the target.
func isSumOf3(xs []int, target int) bool {
	if len(xs) < 3 {
		return false
	}
	sort.Ints(xs)
	highIndx := len(xs) - 1
	for i, x := range xs {
		lowIndx := i + 1
		for lowIndx < highIndx {
			lowVal := xs[lowIndx]
			highVal := xs[highIndx]
			sum := x + lowVal + highVal
			if sum < target {
				lowIndx = lowIndx + 1
			} else if sum > target {
				highIndx = highIndx - 1
			} else {
				return true
			}
		}
	}
	return false
}
func main() {
	xs := []int{-1, 2, 1, -4, 5, -3}
	fmt.Println(isSumOf3(xs, -8))
	xs = []int{1, 2, 3}
	fmt.Println(isSumOf3(xs, 6))
	xs = []int{1, 2, 7}
	fmt.Println(isSumOf3(xs, 6))
}