passcode.c

#include <stdio.h>

void init_input(int *input, size_t psize) {
    for (size_t i = 0; i < psize; i++) {
        input[i] = 99;
    }
}

int check_password(int *password, size_t psize, int *input) {
    for (size_t i = 0; i < psize; i++) {
        if (input[i] > 9) { return -2; } //Means that the input isn't long enough.
        if (password[i] != input[i]) { return -1; } // No need to check more digits.
    }
    return 1;
}
int main() {
    size_t psize = 4;
    int password[] = {1,3,3,7};
    int input[4];
    while(1) {
        init_input(input, psize);
        // This would be your keypad input. Try fucking around with it.
        scanf("%i", &input[0]);
        scanf("%i", &input[1]);
        scanf("%i", &input[2]);
        scanf("%i", &input[3]);
        int val = check_password(password, psize, input);
        if ( val == 1 ) { printf("A-access granted anona-senpai.\n"); }
        else { printf("B-baka, you're not anona-kun!\n"); }
    }
    return 0;
}