#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/mman.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdint.h>
#include <unistd.h>
#include <sys/types.h>
#include <stdlib.h>

int main(int argc, char *argv[]) {
    char *file_name = argv[1];
    int32_t N = strtol(argv[2], NULL, 10);
    int32_t W = strtol(argv[3], NULL, 10);

    size_t length = N * N * W + N;
    int fd = open(file_name, O_RDWR | O_CREAT, 0777);
    ftruncate(fd, length);

    struct stat st;
    fstat(fd, &st);
    char *contents = mmap(NULL,
                          st.st_size,
                          PROT_READ | PROT_WRITE,
                          MAP_SHARED,
                          fd,
                          0);
memset(contents, ' ', st.st_size);
    int *arr;
    arr = (int*)malloc(N * N * sizeof(int));
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            arr[i * N + j] = 0;
        }
    }
    int count = 1;
    int i = 0;
    int j = 0;
    int d = 3;

    while(count != N * N + 1) {
        if (i != N && i != -1 && j != N && j != -1 && arr[i * N + j] == 0) {
            char *cur = contents + i * N * W + j * W + i;
            arr[i * N + j] = 1;
            char *strs = malloc(100 * sizeof(char));
            snprintf(strs, W + 1, "%d", count);
            sprintf(cur + W - strlen(strs), "%s", strs);
        free(strs);
            count++;
            if (d == 0) {
                if (i + 1 == N || arr[(i + 1) * N + j] == 1) {
                    d = 1;
                    j--;
                } else {
                    i++;
                }
            } else if (d == 1) {
                if (j - 1 == -1 || arr[i * N + j - 1] == 1) {
                    d = 2;
                    i--;
                } else {
                    j--;
                }
            } else if (d == 2) {
                if (i - 1 == -1 || arr[(i - 1) * N + j] == 1) {
                    d = 3;
                    j++;
                } else {
                    i--;
                }
            } else if (d == 3) {
                if (j + 1 == N || arr[i * N + j + 1] == 1) {
                    d = 0;
                    i++;
                } else {
                    j++;
                };
            }
        }
    }
    for (int i = 0; i < N; ++i) {
    *(contents + N * W + i * N * W + i) = '\n';
    }
    free(arr);
finally:
    munmap(contents, st.st_size);
    close(fd);
    return 0;
}