CODEWITHSUNDEEP
ccs50
Fernando Velasco Borea
Fernando Velasco Borea

Reputation: 183

CS50's pset3 Tideman... my lock function doesn't seem to work

I've been trying to solve an issue I have with the lock_pairs function. I used recursion to validate if we have a path that follows a cycle (basically, follow the losers path to see if it won against another candidate and checking if we get back to the origin point, effectively forming a cycle).

But I have an issue since it returns an error when using check50 to validate my solution, and I'm way too lost to even think what is wrong, I feel I've checked everything and still it doesn't work.

This is the error from check50:

:( lock_pairs skips final pair if it creates cycle
lock_pairs did not correctly lock all non-cyclical pairs

Here's the code:

    // To be used in lock_pairs to avoid cycles, true means cycles, false means we good
bool check_cycles(int loser_ind, int winner_ind)
{
    // Base case, if the loser path returns to the winner, we have a circle
    if (loser_ind == winner_ind)
    {
        return true;
    }

    for (int i = 0; i < candidate_count; i++)
    {
        if (locked[loser_ind][i]) // If the loser has an edge over another candidate, i.e, if the loser candidate won against another candidate
        {
            return check_cycles(i, winner_ind); // We'll check if that other candidate that lost has a winning path to another candidate
        }
    }

    return false;

}

// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs(void)
{
    // Let's loop on all pairs
    for (int i = 0; i < pair_count; i++)
    {
        // If we didn't created a cycle, we'll register the lock
        if (!check_cycles(pairs[i].loser, pairs[i].winner))
        {
            locked[pairs[i].winner][pairs[i].loser] = true; // It means the i-th pair winner candidate won over i-th pair losing candidate
        }
    }

    return;
}

Upvotes: 0

Views: 297

Answers (1)

birojow
birojow

Reputation: 53

Maybe changing

return check_cycles(i, winner_ind);

to

if (check_cycles(i, winner_ind)){
    return true;
}

would fix it

Upvotes: 1

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