cs50, tideman, lock_pairs - c

Question

I have a problem that I have been struggling with the check_pairs function for several days. Finally, I wrote a version of the code that in my opinion everything is correct and indeed in CS50 everything shows green except :( lock_pairs skips final pair if it creates cycle.
And I found this code:
// Recursive function to check if entry makes a circle
bool makes_circle(int cycle_start, int loser)
{
if (loser == cycle_start)
{
// If the current loser is the cycle start
// The entry makes a circle
return true;
}
for (int i = 0; i < candidate_count; i++)
{
if (locked[loser][i])
{
if (makes_circle(cycle_start, i))
{
// Forward progress through the circle
return true;
}
}
}
return false;
}
// Lock pairs into the candidate graph in order, without creating cycles
void lock_pairs()
{
for (int i = 0; i < pair_count; i++)
{
if (!makes_circle(pairs[i].winner, pairs[i].loser))
{
// Lock the pair unless it makes a circle
locked[pairs[i].winner][pairs[i].loser] = true;
}
}
}
Found it here: PSET 3 Tideman CS50 lock_pairs doesn't lock correctly
When I pasted it to tideman everything was green with check50 and I can't figure out why and how it differs from my function. I checked various combinations in debug50, drew a few pages and still don't understand what is the detail that makes this recursive function different from mine. Could someone explain to me step by step why this function is correct and mine is not?
My code:
void lock_pairs(void)
{
for (int i = 0; i < pair_count; i++)
{
bool cycle = false;
// check if the loser of the actual checking pair won with any other candidate
for (int j = 0; j < candidate_count && !cycle; j++)
{
if (locked[pairs[i].loser][j])
{
// if the loser beats any other candidate, check if this other candidate beats the winner of the actual checking pair
for (int k = 0; k < candidate_count && !cycle; k++)
{
if (locked[j][k])
{
if (k == pairs[i].winner)
{
cycle = true;
}
}
}
}
}
if (!cycle)
{
locked[pairs[i].winner][pairs[i].loser] = true;
}
}
return;
}