README.md

Raindrops

Write a program that converts a number to a string, the contents of which depends on the number's prime factors.

• If the number contains 3 as a prime factor, output 'Pling'.
• If the number contains 5 as a prime factor, output 'Plang'.
• If the number contains 7 as a prime factor, output 'Plong'.
• If the number does not contain 3, 5, or 7 as a prime factor, just pass the number's digits straight through.

Examples

• 28's prime-factorization is 2, 2, 7.
  • In raindrop-speak, this would be a simple "Plong".
• 1755 prime-factorization is 3, 3, 3, 5, 13.
  • In raindrop-speak, this would be a "PlingPlang".
• The prime factors of 34 are 2 and 17.
  • Raindrop-speak doesn't know what to make of that, so it just goes with the straightforward "34".

Source

A variation on a famous interview question intended to weed out the obviously incompetent. view source

raindrops_test.go

package raindrops

import "testing"

var tests = []struct {
    input    int
    expected string
}{
    {1, "1"},
    {3, "Pling"},
    {5, "Plang"},
    {7, "Plong"},
    {6, "Pling"},
    {9, "Pling"},
    {10, "Plang"},
    {14, "Plong"},
    {15, "PlingPlang"},
    {21, "PlingPlong"},
    {25, "Plang"},
    {35, "PlangPlong"},
    {49, "Plong"},
    {52, "52"},
    {105, "PlingPlangPlong"},
    {12121, "12121"},
}

func TestConvert(t *testing.T) {
    for _, test := range tests {
        if actual := Convert(test.input); actual != test.expected {
            t.Errorf("Convert(%d) expected %q, Actual %q", test.input, test.expected, actual)
        }
    }
}