Task: Bulls and cows



C#: using System;

namespace BullsnCows
{
    class Program
    {
        
        static void Main(string[] args)
        {
            int[] nums = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            KnuthShuffle<int>(ref nums);
            int[] chosenNum = new int[4];
            Array.Copy(nums, chosenNum, 4);

            Console.WriteLine("Your Guess ?");
            while (!game(Console.ReadLine(), chosenNum))
            {
                Console.WriteLine("Your next Guess ?");
            }
            
            Console.ReadKey();
        }

        public static void KnuthShuffle<T>(ref T[] array)
        {
            System.Random random = new System.Random();
            for (int i = 0; i < array.Length; i++)
            {
                int j = random.Next(array.Length);
                T temp = array[i]; array[i] = array[j]; array[j] = temp;
            }
        }

        public static bool game(string guess, int[] num)
        {
            char[] guessed = guess.ToCharArray();
            int bullsCount = 0, cowsCount = 0;

            if (guessed.Length != 4)
            {
                Console.WriteLine("Not a valid guess.");
                return false;
            }

            for (int i = 0; i < 4; i++)
            {
                int curguess = (int) char.GetNumericValue(guessed[i]);
                if (curguess < 1 || curguess > 9)
                {
                    Console.WriteLine("Digit must be ge greater 0 and lower 10.");
                    return false;
                }
                if (curguess == num[i])
                {
                    bullsCount++;
                }
                else
                {
                    for (int j = 0; j < 4; j++)
                    {
                        if (curguess == num[j])
                            cowsCount++;
                    }
                }
            }

            if (bullsCount == 4)
            {
                Console.WriteLine("Congratulations! You have won!");
                return true;
            }
            else
            {
                Console.WriteLine("Your Score is {0} bulls and {1} cows", bullsCount, cowsCount);
                return false;
            }
        }
    }
}


Go: package main

import (
    "bufio"
    "bytes"
    "fmt"
    "math/rand"
    "os"
    "strings"
    "time"
)

func main() {
    fmt.Println(`Cows and Bulls
Guess four digit number of unique digits in the range 1 to 9.
A correct digit but not in the correct place is a cow.
A correct digit in the correct place is a bull.`)
    
    pat := make([]byte, 4)
    rand.Seed(time.Now().Unix())
    r := rand.Perm(9)
    for i := range pat {
        pat[i] = '1' + byte(r[i])
    }

    
    valid := []byte("123456789")
guess:
    for in := bufio.NewReader(os.Stdin); ; {
        fmt.Print("Guess: ")
        guess, err := in.ReadString('\n')
        if err != nil {
            fmt.Println("\nSo, bye.")
            return
        }
        guess = strings.TrimSpace(guess)
        if len(guess) != 4 {
            
            fmt.Println("Please guess a four digit number.")
            continue
        }
        var cows, bulls int
        for ig, cg := range guess {
            if strings.IndexRune(guess[:ig], cg) >= 0 {
                
                fmt.Printf("Repeated digit: %c\n", cg)
                continue guess
            }
            switch bytes.IndexByte(pat, byte(cg)) {
            case -1:
                if bytes.IndexByte(valid, byte(cg)) == -1 {
                    
                    fmt.Printf("Invalid digit: %c\n", cg)
                    continue guess
                }
            default: 
                cows++
            case ig:
                bulls++
            }
        }
        fmt.Printf("Cows: %d, bulls: %d\n", cows, bulls)
        if bulls == 4 {
            fmt.Println("You got it.")
            return
        }
    }
}