twonumsum.md

Two-Number Sum

Write a function that takes as parameters a non-empty slice of integers and an integer representing a target sum. Your task is to return the pair of numbers within the input slice that add up to the target sum given. If no numbers in the input slice add up to the given target sum, return an empty slice. You may assume that there will be no more than one pair of numbers from the input slice that add up to the target sum.

Hint: There are several ways to do this which vary in efficiency. First focus on solving it and only then on optimizing it.

You may use the test below to exercise your solution.

twonumsum_test.go

package sum

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestTwoNumberSum(t *testing.T) {
	cases := []struct {
		name     string
		numbers  []int
		sum      int
		expected []int
	}{
		{name: "one", numbers: []int{4, 6}, sum: 10, expected: []int{4, 6}},
		{name: "two", numbers: []int{4, 6, 1}, sum: 5, expected: []int{1, 4}},
		{name: "three", numbers: []int{6, 4}, sum: 10, expected: []int{4, 6}},
		{name: "four", numbers: []int{5, 7, 5}, sum: 10, expected: []int{5, 5}},
		{name: "five", numbers: []int{4, 0, 6}, sum: 10, expected: []int{4, 6}},
		{name: "six", numbers: []int{-5, 5, 15}, sum: 10, expected: []int{-5, 15}},
		{name: "seven", numbers: []int{-1, 5, 15}, sum: 10, expected: []int{}},
		{name: "eight", numbers: []int{1, 2, 3, 4, 5, 6, 7, 8, 9}, sum: 17, expected: []int{8, 9}},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			assert.Equal(t, tc.expected, twoNumberSum(tc.numbers, tc.sum))
		})
	}

}