void reverse(char **s, int start, int end) {
    while (start < end) {
        char *temp = s[start];
        s[start] = s[end];
        s[end] = temp;
        start++;
        end--;
    }
}

int next_permutation(int n, char **s)
{
    int i = n - 2;
    while (i >= 0 && strcmp(s[i], s[i + 1]) >= 0) i--; 
    
    if (i < 0) return 0;
    
    int j = n - 1;
    while (strcmp(s[i], s[j]) >= 0) j--; 
    
    char *temp = s[i];
    s[i] = s[j];
    s[j] = temp;
    
    reverse(s, i + 1, n - 1);
    
    return 1;
}