find how many times one can call rand() in sequence before the values start repeating.

find_sequence_length.c

#include <stdio.h>
#include <stdlib.h>

int main() {
    srand(1);
    int arr[] = {rand(), rand(), rand(), rand()};
    long long n = sizeof(arr) / sizeof(*arr);
    while (true) {
        if (rand() != arr[0]) n += 1;
        else if (rand() != arr[1]) n += 2;
        else if (rand() != arr[2]) n += 3;
        else if (rand() != arr[3]) n += 4;
        else {
            printf("Sequence length: %lli\n", n);
            return 0;
        }
    }
}