#include <dirent.h>
#include <stdlib.h>
#include <memory.h>
#include <stdio.h>
#include <sys/stat.h>


int cmp(const void *a, const void *b)
{
    return strcasecmp(*((char**) a), *((char**) b));
}


void scan_path(char *path, int len, DIR *dir)
{
    static int counter = 0;
    struct dirent *ent;
    size_t size = 1;
    char **buf = calloc(size, sizeof(*buf));
    size_t i = 0;
    while ((ent = readdir(dir)) != NULL) {
        if (strcmp(ent->d_name, ".") && strcmp(ent->d_name, "..")) {
            struct stat st;
            int name_len = snprintf(path + len, (size_t) (PATH_MAX - len), "/%s", ent->d_name);
            if (name_len < PATH_MAX - len && lstat(path, &st) != -1 && S_ISDIR(st.st_mode)) {
                if (i == size) {
                    size *= 2;
                    buf = realloc(buf, size*sizeof(*buf));
                }
                buf[i] = strdup(ent->d_name);
                i++;
            }
        }
    }
    closedir(dir);
    qsort(buf, i, sizeof(*buf), cmp);
    for (int j = 0; j < i; j++) {
        int name_len = snprintf(path + len, (size_t) (PATH_MAX - len), "/%s", buf[j]);
        if ((dir = opendir(path)) != NULL) {
            printf("cd %s\n", buf[j]);
            free(buf[j]);
            scan_path(path, len + name_len, dir);
        } else {
            free(buf[j]);
        }
    }
    if (counter) {
        printf("cd ..\n");
    }
    counter++;
    free(buf);
}


int main(int argc, char *argv[])
{
    if (argc < 2) {
        return 1;
    }
    char *path = argv[1];
    DIR *dir;
    if ((dir = opendir(path)) != NULL) {
        char path1[PATH_MAX + 1];
        sprintf(path1, "%s", path);
        scan_path(path1, (int) strlen(path1), dir);
    }
    return 0;
}