Task: Random Latin squares



C#: using System;
using System.Collections.Generic;

namespace RandomLatinSquares {
    using Matrix = List<List<int>>;

    
    static class Helper {
        private static readonly Random rng = new Random();

        public static void Shuffle<T>(this IList<T> list) {
            int n = list.Count;
            while (n > 1) {
                n--;
                int k = rng.Next(n + 1);
                T value = list[k];
                list[k] = list[n];
                list[n] = value;
            }
        }
    }

    class Program {
        static void PrintSquare(Matrix latin) {
            foreach (var row in latin) {
                Console.Write('[');

                var it = row.GetEnumerator();
                if (it.MoveNext()) {
                    Console.Write(it.Current);
                }
                while (it.MoveNext()) {
                    Console.Write(", ");
                    Console.Write(it.Current);
                }

                Console.WriteLine(']');
            }
            Console.WriteLine();
        }

        static void LatinSquare(int n) {
            if (n <= 0) {
                Console.WriteLine("[]");
                return;
            }

            var latin = new Matrix();
            for (int i = 0; i < n; i++) {
                List<int> temp = new List<int>();
                for (int j = 0; j < n; j++) {
                    temp.Add(j);
                }
                latin.Add(temp);
            }
            
            latin[0].Shuffle();

            
            for (int i = 1; i < n - 1; i++) {
                bool shuffled = false;

                while (!shuffled) {
                    latin[i].Shuffle();
                    for (int k = 0; k < i; k++) {
                        for (int j = 0; j < n; j++) {
                            if (latin[k][j] == latin[i][j]) {
                                goto shuffling;
                            }
                        }
                    }
                    shuffled = true;

                shuffling: { }
                }
            }

            
            for (int j = 0; j < n; j++) {
                List<bool> used = new List<bool>();
                for (int i = 0; i < n; i++) {
                    used.Add(false);
                }

                for (int i = 0; i < n-1; i++) {
                    used[latin[i][j]] = true;
                }
                for (int k = 0; k < n; k++) {
                    if (!used[k]) {
                        latin[n - 1][j] = k;
                        break;
                    }
                }
            }

            PrintSquare(latin);
        }

        static void Main() {
            LatinSquare(5);
            LatinSquare(5);
            LatinSquare(10); 
        }
    }
}


Go: package main

import (
    "fmt"
    "math/rand"
    "time"
)

type matrix [][]int

func shuffle(row []int, n int) {
    rand.Shuffle(n, func(i, j int) {
        row[i], row[j] = row[j], row[i]
    })
}

func latinSquare(n int) {
    if n <= 0 {
        fmt.Println("[]\n")
        return
    }
    latin := make(matrix, n)
    for i := 0; i < n; i++ {
        latin[i] = make([]int, n)
        if i == n-1 {
            break
        }
        for j := 0; j < n; j++ {
            latin[i][j] = j
        }
    }
    
    shuffle(latin[0], n)

    
    for i := 1; i < n-1; i++ {
        shuffled := false
    shuffling:
        for !shuffled {
            shuffle(latin[i], n)
            for k := 0; k < i; k++ {
                for j := 0; j < n; j++ {
                    if latin[k][j] == latin[i][j] {
                        continue shuffling
                    }
                }
            }
            shuffled = true
        }
    }

    
    for j := 0; j < n; j++ {
        used := make([]bool, n)
        for i := 0; i < n-1; i++ {
            used[latin[i][j]] = true
        }
        for k := 0; k < n; k++ {
            if !used[k] {
                latin[n-1][j] = k
                break
            }
        }
    }
    printSquare(latin, n)
}

func printSquare(latin matrix, n int) {
    for i := 0; i < n; i++ {
        fmt.Println(latin[i])
    }
    fmt.Println()
}

func main() {
    rand.Seed(time.Now().UnixNano())
    latinSquare(5)
    latinSquare(5)
    latinSquare(10) 
}