Bridge and Torch Logic Puzzle solved in Go

bridge-torch-puzzle.go

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"os"
	"sort"
	"strings"
)

// MaxParticipants constant describes the max number of participants that will be evaluated
const MaxParticipants = 4

// Participants struct which contains an array of participants
type Participants struct {
	Participants []Participant `json:"participants"`
}

// Participant struct which contains a name and the speed at which the person walks
type Participant struct {
	Name  string `json:"name"`
	Speed int    `json:"speed"`
}

// GetJSONFileStuffInStruct function retrieves the Participants data from the specified JSON file
func GetJSONFileStuffInStruct(filename string) Participants {
	// Initialize our Participants array
	var participants Participants

	filename = strings.TrimSpace(filename)
	jsonFile, err := os.Open(filename)

	// if we os.Open returns an error then handle it
	if err != nil {
		fmt.Println(err)
		os.Exit(1)
	} else {
		// defer the closing of our jsonFile so that we can parse it later on
		defer jsonFile.Close()

		// Read our opened jsonFile as a byte array
		byteValue, _ := ioutil.ReadAll(jsonFile)

		// Deserailize the byteArray which contains the jsonFile's content into 'participants' which we defined above
		json.Unmarshal(byteValue, &participants)
	}
	return participants
}

// main function entry-point of the application
func main() {
	// Check that the caller specific command-line arguments
	if len(os.Args) != 2 {
		fmt.Println("You forgot to specific the Participants JSON file.")
		os.Exit(1)
	}

	// Initialize our Participants array
	filename := strings.TrimSpace(os.Args[1])
	participants := GetJSONFileStuffInStruct(filename)

	// Get the number of participants in the jsonFile
	numberOfParticipants := len(participants.Participants)

	// Check to makesure their are 4 or more participants before proceeding
	if numberOfParticipants <= 3 {
		fmt.Println("This process cannot not work without having more than 3 Participants.")
		os.Exit(1)
	} else if numberOfParticipants > MaxParticipants {
		fmt.Printf("NOTE:  There are %d participants in the '%s', which are %d more than are required\n", numberOfParticipants, filename, (numberOfParticipants - MaxParticipants))
		fmt.Println("for this logic puzzle.  Therefore only the first four particpants will be used,")
		fmt.Println("and the rest ignored.")
		participants.Participants = participants.Participants[:MaxParticipants]
		numberOfParticipants = MaxParticipants
	}

	fmt.Println("")
	fmt.Printf("These are the %d participants to be evaluated:\n", numberOfParticipants)

	var totalSpeed, strategyOneTotalSpeed, strategyTwoTotalSpeed int
	/*
	 * Iterate through every participant within our participants array, and
	 * print out the participant name and speed
	 */
	for index := 0; index < numberOfParticipants; index++ {
		fmt.Printf("%d. Participant %s's speed is %d %s\n", (index + 1), participants.Participants[index].Name, participants.Participants[index].Speed, showMinuteSingularOrPlural(participants.Participants[index].Speed))
		totalSpeed += participants.Participants[index].Speed
	}

	// Sort the list of participant by speed in descending order
	sort.Slice(participants.Participants, func(i, j int) bool {
		return participants.Participants[i].Speed < participants.Participants[j].Speed
	})

	// Print out the first strategy
	fmt.Println("")
	fmt.Printf("1st Strategy:\n")
	for index := 1; index < numberOfParticipants; index++ {
		fmt.Printf("'%s' takes '%s' across in %d %s\n", participants.Participants[0].Name, participants.Participants[index].Name, participants.Participants[index].Speed, showMinuteSingularOrPlural(participants.Participants[index].Speed))
		if index != (numberOfParticipants - 1) {
			fmt.Printf("'%s' returns back across taking %d %s\n", participants.Participants[0].Name, participants.Participants[0].Speed, showMinuteSingularOrPlural(participants.Participants[0].Speed))
		}
	}
	strategyOneTotalSpeed = ((totalSpeed - participants.Participants[0].Speed) + participants.Participants[0].Speed*(numberOfParticipants-1)) - 1
	fmt.Printf("The total crossing will take %d minutes\n", strategyOneTotalSpeed)

	// Print out the second strategy
	fmt.Println("")
	fmt.Printf("2nd Strategy:\n")
	fmt.Printf("'%s' takes '%s' across in %d %s\n", participants.Participants[0].Name, participants.Participants[1].Name, participants.Participants[1].Speed, showMinuteSingularOrPlural(participants.Participants[1].Speed))
	fmt.Printf("'%s' returns back across taking %d %s\n", participants.Participants[0].Name, participants.Participants[0].Speed, showMinuteSingularOrPlural(participants.Participants[0].Speed))
	strategyTwoTotalSpeed = participants.Participants[0].Speed + participants.Participants[1].Speed

	fmt.Printf("'%s' takes '%s' across in %d %s\n", participants.Participants[2].Name, participants.Participants[3].Name, participants.Participants[3].Speed, showMinuteSingularOrPlural(participants.Participants[3].Speed))
	fmt.Printf("'%s' returns back across taking %d %s\n", participants.Participants[1].Name, participants.Participants[1].Speed, showMinuteSingularOrPlural(participants.Participants[1].Speed))
	strategyTwoTotalSpeed += participants.Participants[1].Speed + participants.Participants[3].Speed

	fmt.Printf("'%s' takes '%s' across in %d %s\n", participants.Participants[1].Name, participants.Participants[0].Name, participants.Participants[1].Speed, showMinuteSingularOrPlural(participants.Participants[1].Speed))
	strategyTwoTotalSpeed += participants.Participants[1].Speed

	fmt.Printf("The total crossing effort will take %d minutes\n", strategyTwoTotalSpeed)

	fmt.Println("")
	if strategyOneTotalSpeed == strategyTwoTotalSpeed {
		fmt.Println("Either strategy is recommended, because both are equally fast!")
	} else if strategyOneTotalSpeed < strategyTwoTotalSpeed {
		fmt.Println("The 1st Strategy is recommended, because everyone gets across the bridge the fastest!")
	} else {
		fmt.Println("The 2nd Strategy is recommended, because everyone gets across the bridge the fastest!")
	}
}

// showMinuteSingularOrPlural function returns the singular 'minute' if value is 1; otherwise the plural form 'minutes' is returned
func showMinuteSingularOrPlural(value int) string {
	if value == 1 {
		return "minute"
	}
	return "minutes"
}

bridge-torch-puzzle_test.go

package main

import (
	"fmt"
	"sort"
	"testing"
)

func TestNumberOfParticipants(t *testing.T) {
	// Initialize our Participants array
	participants := GetJSONFileStuffInStruct("participants.json")

	if len(participants.Participants) != 0 {
		// Get the number of participants in the jsonFile
		numberOfParticipants := len(participants.Participants)

		wantValue := 4
		errorWant := fmt.Sprintf("numberOfParticipants was not %d, ", wantValue)

		if numberOfParticipants != wantValue {
			t.Errorf(errorWant+"got: %d, want: %d.", numberOfParticipants, wantValue)
		}
	}
}

func TestSlowestPartcipant(t *testing.T) {
	// Initialize our Participants array
	participants := GetJSONFileStuffInStruct("participants.json")

	if len(participants.Participants) != 0 {
		// Sort the list of participant by speed in descending order
		sort.Slice(participants.Participants, func(i, j int) bool {
			return participants.Participants[i].Speed < participants.Participants[j].Speed
		})

		wantName := "Rachel"
		wantValue := 8
		errorWant := fmt.Sprintf("Slowest Participant is not '{%s %d}', ", wantName, wantValue)

		if participants.Participants[(len(participants.Participants)-1)] != (Participant{Name: wantName, Speed: wantValue}) {
			t.Errorf(errorWant+"got: %v, want: %v.", participants.Participants[(len(participants.Participants)-1)], (Participant{Name: wantName, Speed: wantValue}))
		}
	}
}

func TestFastestPartcipant(t *testing.T) {
	// Initialize our Participants array
	participants := GetJSONFileStuffInStruct("participants.json")

	if len(participants.Participants) != 0 {
		// Sort the list of participant by speed in descending order
		sort.Slice(participants.Participants, func(i, j int) bool {
			return participants.Participants[i].Speed < participants.Participants[j].Speed
		})

		wantName := "Pon"
		wantValue := 1
		errorWant := fmt.Sprintf("Fastest Participant is not '{%s %d}', ", wantName, wantValue)

		if participants.Participants[0] != (Participant{Name: wantName, Speed: wantValue}) {
			t.Errorf(errorWant+"got: %v, want: %v.", participants.Participants[0], (Participant{Name: wantName, Speed: wantValue}))
		}
	}
}

participants.json

{
    "participants":[
        {
            "name": "Shubhangi",
            "speed": 5
        },
        {
            "name": "Pon",
            "speed": 1
        },
        {
            "name": "Rachel",
            "speed": 8
        },
        {
            "name": "Naveen",
            "speed": 2
        }
    ]
}