Task: Random Latin squares
C: #include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>


int randInt(int low, int high) {
    return (rand() % (high - low)) + low;
}


void shuffle(int *const array, const int n) {
    if (n > 1) {
        int i;
        for (i = 0; i < n - 1; i++) {
            int j = randInt(i, n);

            int t = array[i];
            array[i] = array[j];
            array[j] = t;
        }
    }
}


void printSquare(const int *const latin, const int n) {
    int i, j;
    for (i = 0; i < n; i++) {
        printf("[");
        for (j = 0; j < n; j++) {
            if (j > 0) {
                printf(", ");
            }
            printf("%d", latin[i * n + j]);
        }
        printf("]\n");
    }
    printf("\n");
}

void latinSquare(const int n) {
    int *latin, *used;
    int i, j, k;

    if (n <= 0) {
        printf("[]\n");
        return;
    }

    
    latin = (int *)malloc(n * n * sizeof(int));
    if (!latin) {
        printf("Failed to allocate memory.");
        return;
    }

    
    for (i = 0; i < n; i++) {
        for (j = 0; j < n; j++) {
            latin[i * n + j] = j;
        }
    }

    
    shuffle(latin, n);

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

        while (!shuffled) {
            shuffle(&latin[i * n], n);

            for (k = 0; k < i; k++) {
                for (j = 0; j < n; j++) {
                    if (latin[k * n + j] == latin[i * n + j]) {
                        goto shuffling;
                    }
                }
            }
            shuffled = true;

        shuffling: {}
        }
    }

    
    used = (int *)malloc(n * sizeof(int));
    for (j = 0; j < n; j++) {
        memset(used, 0, n * sizeof(int));
        for (i = 0; i < n - 1; i++) {
            used[latin[i * n + j]] = 1;
        }
        for (k = 0; k < n; k++) {
            if (used[k] == 0) {
                latin[(n - 1) * n + j] = k;
                break;
            }
        }
    }
    free(used);

    
    printSquare(latin, n);
    free(latin);
}

int main() {
    
    srand((unsigned int)time((time_t)0));

    latinSquare(5);
    latinSquare(5);
    latinSquare(10);

    return 0;
}

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); 
        }
    }
}