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;
}

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) 
}