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Archive for March 2009

Most annoying Euler problem yet

In Problem 54, you receive a set of poker hands, and are asked to count the number of times Player 1 won. No algorithmic or mathematical intelligence here, just coding. I advise skipping it in favor of more interesting problems.

Some say the Chinese word for “crisis” is composed of “danger” and opportunity (others do not). I took the time to play with LINQ and lambdas for the first time (in C# at least), and it was a great deal of fun – even at my home computer which is currently suffering from lack of Resharper.

SPOILER SPOILER SPOILER

Here’s a bit of LINQ goodness. The method I used (SPOILER SPOILER) to calculate the winner of two similar hands is a weighted sum. I summed all the best cards with a high weight, then added less important cards with lower weight (for example, 3 twos get more weight each than 2 kings in the same hand).

Once I found which value is the best in a given hand (2 in the above hand), I used this little one liner to count the number of cards equal to the maximal value.

_cards.Where(c => c.Value == bestValue).Count();

Terse is the new black.

Problem 99 on Project Euler

I wonder why problem 99 is rated this difficult (there are 62 other problems considered easier). True, it can’t be brute-forced, but it only uses a tiny bit of high school math (compared to say problem 69, which is relatively much harder IMO – see Eli’s post for its solution – but is rated roughly the same).