2010-06-01

Programming Challenges: 110208 Yahtzee

I completed the Yahtzee problem today, after a couple of days effort.

I first double checked my previous 2004 solution’s scoring function, there were a few gems in there that I had to reproove, like how the full house was worked out.

// a - e are the five dice rolls
int array[7] = { 0,0,0,0,0,0,0 };

array[a]++;
array[b]++;
array[c]++;
array[d]++;
array[e]++;

// full house
if ( ( array[a] + array[b] + array[c] + array[d] + array[e] ) == 13 )
{
    scores[count][12] = 40;
}

I then rewrote the recursive function to remove my fancy std::list<int> stuff and used simple arrays of ints, and wrote a completely naive checker. But at 6 billions checks per score set, it was never going to fit the time limit.

I then thought about it for a day, and this morning, wrote a version the skipped the skippable stuff, but it got the wrong answer, then I noticed a case I’d skipped that I shouldn’t have. I added that back in, and all of a sudden my code started giving really bad (low) score results.

I noticed the my best score function was entering (new_score > best_score) when they were the same values.

Much muttering, explaining to my wife and children later…

I noticed a compiler warning:

warning C4390: ';' : empty controlled statement found; is this the intent?

from this:

if( new_value > best_value );
{
    //cout << "b: " << best_value << " n: " << new_value << endl;
    memcpy(best_set, current_set, sizeof(int)*13);
    best_value = new_value;
}

after removing the stupid semicolon and debugging text, my solution solved the puzzle!