// Check if there is still cycles in the graph or not
bool is_cycle()
{
    int stack[candidate_count];
    int visited[candidate_count];
    for (int i = 0; i < candidate_count; i++)
    {
        visited[i] = -1;
    }
    int stack_pointer = -1;

    stack[++stack_pointer] = 0;
    while (stack_pointer >= 0)
    {
        int pop = stack[stack_pointer--];
        if (visited[pop] == 0)
        {
            visited[pop] = 1;
        }
        if (visited[pop] == -1)
        {
            visited[pop] = 0;
        }

        for (int i = 0; i < candidate_count; i++)
        {
            if (locked[pop][i] && visited[i] == 1)
            {
                return true;
            }
            if (locked[pop][i])
            {
                stack[++stack_pointer] = i;
            }
        }
    }
    return false;
}

// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs(void)
{
    for (int i = 0; i < pair_count; i++)
    {
        int winner = pairs[i].winner;
        int loser = pairs[i].loser;

        locked[winner][loser] = true;
        if (is_cycle())
        {
            locked[winner][loser] = false;
        }
    }
    return;
}