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artemkorsakov's solution

to Proverb in the Go Track

Published at Feb 21 2019 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

For want of a horseshoe nail, a kingdom was lost, or so the saying goes.

Given a list of inputs, generate the relevant proverb. For example, given the list ["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"], you will output the full text of this proverbial rhyme:

For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the message was lost.
For want of a message the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a nail.

Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content. No line of the output text should be a static, unchanging string; all should vary according to the input given.

Running the tests

To run the tests run the command go test from within the exercise directory.

If the test suite contains benchmarks, you can run these with the --bench and --benchmem flags:

go test -v --bench . --benchmem

Keep in mind that each reviewer will run benchmarks on a different machine, with different specs, so the results from these benchmark tests may vary.

Further information

For more detailed information about the Go track, including how to get help if you're having trouble, please visit the exercism.io Go language page.

Source

Wikipedia http://en.wikipedia.org/wiki/For_Want_of_a_Nail

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

cases_test.go

package proverb

// Source: exercism/problem-specifications
// Commit: e86e97a proverb: apply "input" policy
// Problem Specifications Version: 1.1.0

type proverbTest struct {
	description string
	input       []string
	expected    []string
}

var stringTestCases = []proverbTest{
	{
		description: "zero pieces",
		input:       []string{},
		expected:    []string{},
	},
	{
		description: "one piece",
		input:       []string{"nail"},
		expected:    []string{"And all for the want of a nail."},
	},
	{
		description: "two pieces",
		input:       []string{"nail", "shoe"},
		expected:    []string{"For want of a nail the shoe was lost.", "And all for the want of a nail."},
	},
	{
		description: "three pieces",
		input:       []string{"nail", "shoe", "horse"},
		expected:    []string{"For want of a nail the shoe was lost.", "For want of a shoe the horse was lost.", "And all for the want of a nail."},
	},
	{
		description: "full proverb",
		input:       []string{"nail", "shoe", "horse", "rider", "message", "battle", "kingdom"},
		expected:    []string{"For want of a nail the shoe was lost.", "For want of a shoe the horse was lost.", "For want of a horse the rider was lost.", "For want of a rider the message was lost.", "For want of a message the battle was lost.", "For want of a battle the kingdom was lost.", "And all for the want of a nail."},
	},
	{
		description: "four pieces modernized",
		input:       []string{"pin", "gun", "soldier", "battle"},
		expected:    []string{"For want of a pin the gun was lost.", "For want of a gun the soldier was lost.", "For want of a soldier the battle was lost.", "And all for the want of a pin."},
	},
}

proverb_test.go

package proverb

import (
	"fmt"
	"testing"
)

func TestProverb(t *testing.T) {
	for _, test := range stringTestCases {
		actual := Proverb(test.input)
		if fmt.Sprintf("%q", actual) != fmt.Sprintf("%q", test.expected) {
			t.Fatalf("Proverb test [%s], expected [%s], actual [%s]", test.input, test.expected, actual)
		}
	}
}

func BenchmarkProverb(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for _, test := range stringTestCases {
			Proverb(test.input)
		}
	}
}
package proverb

import "fmt"

// Proverb generates the relevant proverb.
func Proverb(rhyme []string) []string {
	result := make([]string, len(rhyme))
	for i := 0; i < len(rhyme)-1; i++ {
		result[i] = GetNotLastRow(rhyme[i], rhyme[i+1])
	}
	if len(rhyme) > 0 {
		result[len(result)-1] = GetLastRow(rhyme[0])
	}
	return result
}

// GetNotLastRow returns not last row of the proverb.
func GetNotLastRow(first string, second string) string {
	return fmt.Sprintf("For want of a %s the %s was lost.", first, second)
}

// GetLastRow returns last row of the proverb.
func GetLastRow(str string) string {
	return fmt.Sprintf("And all for the want of a %s.", str)
}

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