segmentation fault when using larger values in Tideman

Question

I'm incredibly stuck at this excercise. I'm just starting out Cs50x 2024.

I thought I had finished it and was about to cry of happiness, but when testing more candidates and voters it crashed with a segmentation error at, let's say, comparing locked pairs after i = 10, 13 or more.

Ok I have tried checking what segmentation fault is, made some changes, still I think somethin's happening with j at check_cycle function, but can't just grasp the idea, maybe because I'm burnout lol.

I haven't wanted to check this problem's solution online because I almost got it myself and it wouldn't make me trully understand what's happening for future problems.

Thanks in advance for your time

#include <cs50.h>
#include <stdio.h>
#include <string.h>

// Max number of candidates
#define MAX 9

// preferences[i][j] is number of voters who prefer i over j
int preferences[MAX][MAX];

// locked[i][j] means i is locked in over j
bool locked[MAX][MAX];

// Each pair has a winner, loser
typedef struct
{
    int winner;
    int loser;
} pair;

// Array of candidates
string candidates[MAX];
pair pairs[MAX * (MAX - 1) / 2];

int pair_count;
int candidate_count;

// Function prototypes
bool vote(int rank, string name, int ranks[]);
void record_preferences(int ranks[]);
void add_pairs(void);
void sort_pairs(void);
void lock_pairs(void);
void print_winner(void);
bool check_cycle(int winner_tested, int loser_tested, int current_pair);
bool is_source(int candidate);

int main(int argc, string argv[])
{
    // Check for invalid usage
    if (argc < 2)
    {
        printf("Usage: tideman [candidate ...]\n");
        return 1;
    }

    // Populate array of candidates
    candidate_count = argc - 1;
    if (candidate_count > MAX)
    {
        printf("Maximum number of candidates is %i\n", MAX);
        return 2;
    }
    for (int i = 0; i < candidate_count; i++)
    {
        candidates[i] = argv[i + 1];
    }

    // Clear graph of locked in pairs
    for (int i = 0; i < candidate_count; i++)
    {
        for (int j = 0; j < candidate_count; j++)
        {
            locked[i][j] = false;
        }
    }

    pair_count = 0;
    int voter_count = get_int("Number of voters: ");

    // Query for votes
    for (int i = 0; i < voter_count; i++)
    {
        // ranks[i] is voter's ith preference
        int ranks[candidate_count];

        // Query for each rank
        for (int j = 0; j < candidate_count; j++)
        {
            string name = get_string("Rank %i: ", j + 1);

            if (!vote(j, name, ranks))
            {
                printf("Invalid vote.\n");
                return 3;
            }
        }

        record_preferences(ranks);

        printf("\n");
    }

    add_pairs();
    sort_pairs();
    lock_pairs();
    print_winner();
    return 0;
}

// Update ranks given a new vote
bool vote(int rank, string name, int ranks[])
{
    for (int i = 0; i < candidate_count; i++)
        {
            if (strcmp(name, candidates[i]) == 0)
            {
                ranks[rank] = i;
                return true;
            }
        }
    return false;
}

// Update preferences given one voter's ranks
void record_preferences(int ranks[])
{
    for (int i = 0; i < candidate_count; i++)
    {

        for (int j = i + 1; j < candidate_count; j++)
        {
             preferences[ranks[i]][ranks[j]]++;
             printf("%s over %s is %i \n", candidates[ranks[i]], candidates[ranks[j]], preferences[ranks[i]][ranks[j]]);
        }

    }
}

// Record pairs of candidates where one is preferred over the other
void add_pairs(void)
{
    for (int i = 0; i < candidate_count; i++)
    {
        for (int j = 0; j< candidate_count; j++)
        {
            if ( preferences[i][j] > preferences[j][i])
            {
               pairs[pair_count].winner = i;
               pairs[pair_count].loser = j;
               printf("%s wins over %s for %i to %i \n",  candidates[pairs[pair_count].winner], candidates[pairs[pair_count].loser], preferences[i][j], preferences[j][i]);
               pair_count++;
            }
        }
    }

}

// Sort pairs in decreasing order by strength of victory
void sort_pairs(void)
{

    for (int i =  pair_count - 1; i >= 1; i--)
    {
        int sorts = 0;
        for (int j = 0; j <= i - 1; j++)
        {
            if( preferences[pairs[j].winner][pairs[j].loser] < preferences[pairs[j + 1].winner][pairs[j + 1].loser] )
            {
                int temp1 = pairs[j].winner;
                int temp2 = pairs[j].loser;

                pairs[j].winner = pairs[j + 1].winner;
                pairs[j].loser = pairs[j + 1].loser;

                pairs[j + 1].winner = temp1;
                pairs[ j + 1].loser = temp2;
                sorts = 1;

            }
         }

        if( sorts == 0 )
        {
            break;
        }


    }

    for (int i = 0; i < pair_count; i++)
        {
            printf(" %i - %s beats %s, [%i][%i]\n", i + 1 , candidates[pairs[i].winner], candidates[pairs[i].loser], preferences[pairs[i].winner][pairs[i].loser], preferences[pairs[i].loser][pairs[i].winner]);
        }
        printf("pair count = %i", pair_count );
}

// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs(void)
{
    //locking first two pairs, since they can't create cycles with each other (there are no pairs with tied candidates)
    locked[pairs[0].winner][pairs[0].loser] = true;
    locked[pairs[1].winner][pairs[1].loser] = true;

    for(int i = 2; i < pair_count; i++)
    {
        //check if winner is looser in a previous pairs.

        if(check_cycle(pairs[i].winner, pairs[i].loser, i))
        {
            locked[pairs[i].winner][pairs[i].loser] = false;
            printf("Arrow from %s\n to  %s\n can't be locked", candidates[pairs[i].winner], candidates[pairs[i].loser]);
        }
        else
        {
            locked[pairs[i].winner][pairs[i].loser] = true;
            printf("Arrow from %s to  %s locked\n", candidates[pairs[i].winner], candidates[pairs[i].loser]);

        }

    }
    return;
}

// Print the winner of the election
void print_winner(void)
{
    for(int i = 0; i < candidate_count; i++)
    {

       if(is_source(i))
       {
            return;
       }

    }
}

bool check_cycle(int winner_tested, int loser_tested, int current_pair)
{
    bool forms_cycle = false;

    for (int j = 0; j < current_pair; j++)
    {
        int loopwinner = pairs[j].winner;
        int looploser = pairs [j].loser;

        if( winner_tested == pairs[j].loser)
        {
                if (pairs[j].winner == loser_tested)
                {
                    if(locked[pairs[j].winner][winner_tested])
                    {
                        return true;
                    }

                }
                else
                {
                   forms_cycle = check_cycle(pairs[j].winner, loser_tested, current_pair);
                }

        }
    }
    if(!forms_cycle)
    {
        return false;
    }
    else
    {
        return true;
    }


 }

bool is_source(int candidate)
{
    int wins = 0;
    for (int i = 0; i < pair_count; i++)
        {
            printf("comparing pair %i, where %s is winner and %s is looser and is locked %d\n", i, candidates[pairs[i].winner], candidates[pairs[i].loser], locked[pairs[i].winner][pairs[i].loser]);
            if(pairs[i].loser == candidate)
            {
                if(locked[pairs[i].winner][candidate])
                {
                    return false;
                }

            }
            else if (pairs[i].winner == candidate)
            {
                //just to check if there's a pair with this candidate.
                wins++;
            }
            else
            {
                break;
            }

        }
        if (wins > 0)
        {
        printf("Winner is %s\n", candidates[candidate]);
        return true;
        }
        else
        {
            return false;
        }

}