Q7 Poker Hand

[Zita Lifland]

Inpoker, players form sets of five playing cards, called hands, according to the rules of the game.[1] Each hand has a rank, which is compared against the ranks of other hands participating in the showdown to decide who wins the pot.[2] In high games, like Texas hold 'em and seven-card stud, the highest-ranking hands win. In low games, like razz, the lowest-ranking hands win. In high-low split games, both the highest-ranking and lowest-ranking hands win, though different rules are used to rank the high and low hands.[3][4]

Each hand belongs to a category determined by the patterns formed by its cards. A hand in a higher-ranking category always ranks higher than a hand in a lower-ranking category. A hand is ranked within its category using the ranks of its cards. Individual cards are ranked, from highest to lowest: A, K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3 and 2.[5] However, aces have the lowest rank under ace-to-five low or ace-to-six low rules, or under high rules as part of a five-high straight or straight flush.[6][7] Suits are not ranked, so hands that differ by suit alone are of equal rank.[8]

I am thinking about poker hand (5 cards) evaluation in Java. Now I am looking for simplicity and clarity rather than performance and efficiency. I probably can write a "naive" algorithm but it requires a lot of code.

Other solutions involve more compressed tables with more complex indexing, but they are readily comprehensible and pretty fast (although much slower than 2+2). This is where you see language concerning hashing and so forth -- tricks to reduce a table size to more manageable sizes.

In any case, lookup solutions are orders of magnitude faster than the histogram-sort-dance-on-your-head-compare-special-case-and-by-the-way-was-it-a-flush solutions, almost none of which are worthy of a second glance.

(This one is actually written in JavaScript, but you can evaluate JavaScript from Java if needed, so it shouldn't be a problem. Also, this is as short as it gets, so if even for illustration of the approach...):

I have written a poker hand evaluator in both C++ and Javascript. Basically the program would convert a randomly picked set of cards to a 3d array of 1s and 0s. By converting the cards into this format I was then able to write functions that would test for each type of hand starting from the highest.

So in recap, my program would generate random cards, convert them into a 3D array of hearts, diamonds, spades and clubs, where 1 represented one of the cards I had. I would then test the 3D array to see if I had a Royal Flush, Then Straight Flush, Then 4 of a Kind until a match was detected. Once a match was detected say after testing for a flush, then my program wouldn't have to test for straight, 3 of a kind, etc as a flush beats a straight.

If you wanted to test for 7 cards instead of 5 you could also use this system. You can include the users 2 cards with the 5 on the table and run it through my system. You can also do the same for other players at the table and compare the results.

If you are representing a hand as an array of, for example, Card objects, then I would have methods for looping through this array and determining if it has a 2-of-a-kind, flush etc - and if it does, what type it is; so you could have the 3ofaKind() method return 5 if a hand had three 5s. Then I would establish a hierarchy of possibilities (e.g. 3 of a kind is higher than 2 of a kind) and work from there. The methods themselves should be pretty straightforward to write.

high card is not scored! (If you tie on a high card you need to keep checking for the next card etc...) If you want to encode that in your evaluator you would really need bitcode and the program would be less understandable. Fortunately enough, it is easy to check high card on two sorted hands so you first check score. If score is equal you check high card to break the tie ;-)

I am working on a poker game. So far I am stuck on comparing poker hands. I sort of have an idea on how to do it but I am not sure what is wrong with my code. Can somebody please point out what's wrong?

So what I am trying to do above is first, I run through the array, and if if there is any 3. If there is a 3, I run through the array again and see if there is a 2. and if there is not a 2, then I know it is three of a kind. If there is a 2, then it is full house and I should return false. I think my logic is correct, but there is something wrong with my code.

For this one, I am thinking of sort the value in the array either in descending or ascending order. If I chose the descending order, I first read the array and see if there is a 2, then I could scan the next one and see if the next value after the first 2 is also a 2. If there is another 2, then it would return false.

This doesn't directly answer your question, but in my opinion this sort of code is much more readable and maintainable and will be easier to debug than one involving only integers. Java isn't C and you don't really gain much by treating it like C.

Another thing you could do is have filters for each recognized hand: a pair-filter, a three-filter, a full-house-filter, etc. and run all those filters through the hand. Don't worry if there is a better (higher value) match, just see which filters return true (found the pattern they were looking for) and select the highest point value among the ones that passed

First sort your cards from lowest to highest 2 to Ace regardless of suit.Then do comparing.If card[0]==card[3] or card[1]==card[4], you have 4 of a kind, ignore next 2 lines.If card[0]==card[2] or card[1]==card[3] or card[2]==card[4], you have 3 of a kind, ignore the next line.If card[0]==card[1] or card[1]==card[2] or card[2]==card[3] or card[3]==card[4], you have a pair.

One of the first steps towards learning how to play poker is to learn the poker hand rankings. If you want to know what beats what in poker, you can use our OFFICIAL poker hands rankings chart and see all poker hands ranked from best to worst!

While this may seem obvious, it's easy to get your flushes mixed up with your straights, and not remember that a straight flush beats four-of-a-kind. In particular, poker hand rankings is not something that new players to the game are going to instantly know. However, it's such an important aspect of the game and is vital to learn.

Download our FREE printable Poker Hand Rankings Guide as a PDF. We've collated all the information above in an easy-to-read poker cheat sheet of hand rankings, so you can quickly get to terms with what hands beat what in poker.

How many cards are there in a deck? The answer is that there are 52 cards in a standard deck of playing cards. These are all used in a game of poker and, in contrast to games like Blackjack where multiple decks are used, just one deck of cards is used in poker.

Jokers are not used in poker, and all suits of cards are equal. That's not to say that suits are irrelevant, as they can be used to form straights and straight flushes, but no one suit is better or worse than any other. Alternatively, the value of the cards themselves are relevant. Aces are 'high' and 'low' in poker and as such are the greatest value card. They can be used, though, to form the lower end of a wheel straight - A,2,3,4,5. Here, they effectively have a value of 1.

Not quite as prestigious and nowhere near as rare as a Royal, a Straight Flush is the next best hand in poker. A Straight Flush involves five of the same-suited cards but they don't have to be the ace, king, queen, jack and ten. For this reason, they are far more common than Royals, but are still rare. A Straight Flush is the second best hand in poker and can only be beaten by a Royal Flush (or a higher Straight Flush).

Four-of-a-kind, also known as 'Quads' is the third best hand in poker. It consists of four of the same value card, for instance four aces. It is a very strong hand and can only be beaten by Royal or Straight Flushes (or a higher four-of-a-kind).

A Flush in poker is five cards that all have the same suit. It doesn't matter which suit it is as all suits are equal, but if you have five cards that are all the same suit, for instance five diamonds, then you have a Flush. The strength of the Flush is determined by its highest card, followed by its second highest and so on. This comes into play if two or more players have a Flush.

In poker, 3-of-a-kind is three cards of the same value with two other random cards, for instance three kings, a two and a five. Three-of-a-kind is a decent poker hand in poker. If two hands have 3-of-a-kind, the highest numeric value of the 3-of-a-kind wins.

Two Pair in poker is two different numeric pairs and one other unpaired card. If two hands have Two Pair, then the winner is determined by the higher pair. If those are equal, it goes to the highest value of the second pair. If those are also equal, the tiebreaker is the kicker (the fifth, unpaired card).

One Pair in poker is two cards of equal value combined with three unrelated cards. In matchups involving One Pair hands, the highest pair wins. If pairs match, the highest unpaired cards, or kickers, are compared.

You can win without having to show your cards if you force someone to fold before the river. Nonetheless, for the purpose of this article, we'll pretend that we've gone to showdown and need to know what beats what in poker.

Many consider poker less of a gambling game than other casino games. For that to be true, players need to improve their understanding of game play and the strategy required to be a winning player.

A Full House beats a Flush in poker and is a better hand. While Flushes tend to look attractive and in themselves are strong hands, the rarity of making a Full House makes it the better hand of the two.

Four-of-a-kind is rare in poker, but regular poker players will see this hand come up a few times in a week depending on how many times they play. It's even more rare to see two four-of-a-kinds in the same hand, but again, it does happen. In this instance, when four-of-a-kind is up against another four-of-a-kind, the highest value four-of-a-kind wins. If both are equal, it goes down to the unrelated fifth card (the kicker), with the hand with the highest-value kicker winning.

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