• Poker Card Value Guide
• Poker Hands Ranked

Planning Poker is an agile estimating and planning technique that is consensus based. To start a poker planning session, the product owner or customer reads an agile user story or describes a feature to the estimators. Each estimator is holding a deck of Planning Poker cards with values like 0, 1. Blackjack Card Values. Blackjack is a game in which precise values are assigned to each card in the deck. These blackjack card values never change no matter where you play. They remain true for online blackjack and they are also true in a live casino. The blackjack card values are: Ace = 1 or 11; 2-9 = Face Value; 10, J, Q, K = 10.

• General principles
  • Betting limits
• Principal forms
  • Stud poker
  • Community-card poker
  • House-banked games

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Poker, card game, played in various forms throughout the world, in which a player must call (i.e., match) the bet, raise (i.e., increase) the bet, or concede (i.e., fold). Its popularity is greatest in North America, where it originated. It is played in private homes, in poker clubs, in casinos, and over the Internet. Poker has been called the national card game of the United States, and its play and jargon permeate American culture.

Although countless variants of poker are described in the literature of the game, they all share certain essential features. A poker hand comprises five cards. The value of the hand is in inverse proportion to its mathematical frequency; that is, the more unusual the combination of cards, the higher the hand ranks. Players may bet that they have the best hand, and other players must either call (i.e., match) the bet or concede. Players may bluff by betting that they have the best hand when in fact they do not, and they may win by bluffing if players holding superior hands do not call the bet.

General principles

There are forms of poker suitable to any number of players from 2 to 14, but in most forms the ideal number is 6, 7, or 8 players. The object is to win the “pot,” which is the aggregate of all bets made by all players in any one deal. The pot may be won either by having the highest-ranking poker hand or by making a bet that no other player calls. The following principles apply to nearly all forms of poker.

Cards

Poker is almost always played with the standard 52-card deck, the playing cards in each of the four suits (spades, hearts, diamonds, clubs) ranking A (high), K, Q, J, 10, 9, 8, 7, 6, 5, 4, 3, 2, A (low only in the straight [a series of five cards numbered consecutively] or straight flush [a series of five cards numbered consecutively within the same suit] 5-4-3-2-A and in certain variants described below).

In social play, especially in “dealer’s choice” (i.e., a card-playing session in which each player takes a turn at dealing the cards and selecting the game), certain cards may be designated wild cards. A wild card stands for any other card its holder wishes to name. There are many methods of introducing wild cards into the game. The most popular are:

1. Joker. A 53-card pack is used, including the joker as a wild card.
2. Bug. The same 53-card pack including the joker is used, but the joker—here called the bug—counts only as a fifth ace or to fill a flush [a series of five cards of the same suit], a straight, or certain special hands.
3. Deuces wild. All four deuces (2s) are wild cards.
4. One-eyes. In the standard pack the king of diamonds, jack of spades, and jack of hearts are the only cards shown in profile. They are often designated as wild cards.

Rank of poker hands

The rank of standard poker hands is determined by their odds (probability). Two or more identical hands tie and divide any winning equally. The suits have no relative rank in poker. When there is any wild card in the game, the highest possible hand is five of a kind, which beats any straight flush. When there are several wild cards, there may be identical fours of a kind or threes of a kind, in which case ties are broken by the highest unmatched cards or secondary pairs (in a full house [a five-card hand made up of three of a kind and a pair]).

Deal

At the start of the game, any player takes a pack of cards and deals them in rotation to the left, one at a time faceup, until a jack appears. The player receiving that card becomes the first dealer. The turn to deal and the turn to bet always pass to the left from player to player. For each deal, any player may shuffle the cards, the dealer having the last right to shuffle. The dealer must offer the shuffled pack to the opponent to the right for a cut. If that player declines to cut, any other player may cut.

A professional dealer is used in poker clubs, casinos, and tournament play, where a round disc (known as a dealer button) is passed clockwise each hand to indicate the nominal dealer for betting purposes. Also, such environments almost invariably charge the players either by setting an hourly rental fee for their seats or by “raking” a small percentage (say, 5 percent) from each pot.

Betting procedure

In each deal there are one or more betting intervals according to the specific poker variant. In each betting interval, one player, as designated by the rules of the variant being played, has the privilege or obligation of making the first bet. This player and each player in turn after him must place in the pot the number of chips (representing money, for which poker is almost invariably played) to make his total contribution to the pot at least equal to the total contribution of the player before him. When a player does this, he is said to be in the pot, or an active player. If a player declines to do this, he discards his hand and is said to drop or fold, and he may no longer compete for the pot.

Before the deal, each player may be required to make a contribution to the pot, called an ante. In each betting interval, the first player to make a bet is said to bet, a player who exactly meets the previous bet is said to call, and a player who bets more than the previous bettor is said to raise. In some variants, a player is permitted to check, which is to stay in without betting, provided no other player has made a bet in that betting interval. Since a player cannot raise his own bet, each betting interval ends when the betting turn has returned to the person who made the last raise or when all players have checked.

At the end of each betting interval except the last, dealing is resumed. At the end of the last betting interval, there is the “showdown,” in which each active player shows his full hand, and the highest-ranking hand wins the pot.

Betting limits

There are “no-limit” or “sky’s-the-limit” games, but in practice most poker games place some limit on what one may bet in any game. There are three popular methods.

Fixed limit

In fixed-limit games, no one may bet or raise by more than the established limit. In draw poker the limit is usually twice as much after the draw as before—for example, two chips before the draw, four chips after. In stud poker the limit is usually twice as much in the final betting interval as in previous betting intervals. (The higher limit applies also when any player’s exposed cards include a pair.) These respective forms of the game are described below. In a fixed-limit game a limit is usually placed on the number of raises that may be made in any betting interval.

Pot limit

In pot-limit contests, a player may bet or raise by no more than the amount in the pot at the time the bet or raise is made. When raising, the player may first put in the pot the number of chips required to call the previous bet and then raise by the number of chips in the pot. When pot limit is played, it is customary also to place a maximum limit on any bet or raise, regardless of the size of the pot.

Table stakes

This method most closely approximates the no-limit game. Each player’s limit is the number of chips he has on the table at the beginning of the deal. He may not bet more, but for this amount he may call any higher bet (go “all in”) and compete for the pot in the showdown. Other players having more chips may continue to bet, but their further bets go into one or more side pots in the manner decided among the players who contributed fully to the side pot. When a player drops out of any side pot, he drops out of the original pot as well, in effect surrendering his rights in the original pot to the player whose later bet he did not call. Thus, there may be different winners of the main pot and various side pots.

Last Updated on January 1, 2018

I recently took a Hackerrank challenge for a job application that involved poker. I'm not a poker player, so I had a brief moment of panic as I read over the problem the description. In this article I want to do some reflection on how I approached the problem.

The hackerrank question asked me to write a program that would determine the best poker hand possible in five-card draw poker. We are given 10 cards, the first 5 are the current hand, and the second 5 are the next five cards in the deck. We assume that we can see the next five cards (they are not hidden). We want to exchange any n number of cards (where n <= 5) in our hand for the next n cards in the deck. For example, we can take out any combination of 2 cards from the hand we are given, but we must replace these two cards with the next two cards from the deck (we can't pick any two cards from the deck).

Suit and value make up the value of playing cards. For example, you can have a 3 of clubs. 3 is the value, clubs is the suit. We can represent this as 3C.

Suits

Clubs CSpades SHeart HDiamonds D

Value (Rank)

2, 3, 4, 5, 6, 7, 8, 9, 10, Jack, Queen, King, Ace

Hands

Here are the hands of poker

1. Royal flush (the problem didn't ask me to consider Royal Flush)

   A, K, Q, J, 10, all the same suit.

2. Straight flush

   Five cards in a sequence, all in the same suit. Ace can either come before 2 or come after King.

3. Four of a kind

   All four cards of the same rank.

4. Full house

   Three of a kind with a pair.

5. Flush

   Any five cards of the same suit, but not in a sequence.

6. Straight

   Five cards in a sequence, but not of the same suit.

7. Three of a kind

   Three cards of the same rank.

8. Two pair

   Two different pairs.

9. Pair

   Two cards of the same rank.

10. High Card

    When you haven't made any of the hands above, the highest card plays.In the example below, the jack plays as the highest card.

Evaluating a hand of cards

A hand is five cards. The first thing I did was write out functions to evaluate if a group of 5 cards satisfies the conditions of one of the ten hands.

Here's a sample hand:

To write functions, I reached for using 2 important python features: set and defaultdict.

Here's an example of a simple function to detect a flush, a hand with cards of all the same suit:

Checking a flush

This function creates a list of the suits in our hand, and then counts the unique elements in that list by making it a set. If the length of the set is 1, then all the cards in the hand must be of the same suit.

But wait, what if we have a straight flush? Also, a hand that satisfies a flush could also be described as a two pair hand. The problem asked me to find the highest possible hand for a given set of cards, so I tried to keep things simple by writing a check_hand() function that checks each hand starting from straight flush down to high card. As soon as a condition for a hand was satisfied, I returned a number that corresponded to the strength of the hand (1 for high card up to 10 for straight flush). The problem didn't include Royal flush, so I will not include that here.

Here's the check_hand function:

This function starts checking the most valuable hands. After it checks the second to lowest hand (pair), it returns a value of 1. This value of 1 corresponds to the 'highest card' hand. Since I'm not comparing the relative value of hands, it doesn't matter what the highest card is, so the number just represents the type of hand that is the strongest.

Other hands

Here are the all of the functions I used to detect hands:

defaultdict is a great built-in that is good to use when you don't know what elements will be in your dictionary, but you know what the initial values of any key that could be added should be. We don't need it here, but the alternative would be to write a very long dictionary where keys are the possible card values and the values of each key is 0.

It would certainly be cleaner and more efficient to write out the above functions into one large function, but I wanted to keep things simple as I was under time constraints.

The next step in the problem is to determine the best possible hand we can get given the hand we are dealt and the 5 cards on top of the deck. I decided to first solve this problem with brute force. Here was my logic for this part: use itertools to get all combinations of groups of 0, 1, 2, 3, 4 and 5 cards from my hand and add the first 5 - n cards from the deck so we get a five card deck. For each combination of cards we can run check_hand() and keep track of the highest rank hand, and then return that hand as the best hand. Here's the code I wrote for this part of the problem:

Lastly, I need to check each hand and print out the best hand possible. Here's the loop I wrote to do this:

This will accept one round of cards per line:

Poker Card Value Guide

Poker Hands Ranked

and it will output the following:

This was an interesting problem to deal with as the solution contained several parts that worked together. While solving the problem I aimed worked through to the end leaving some parts to come back to that I felt confident in solving. Instead of writing each function to check differnt hands at the beginning, I filled most of these functions with pass and moved on to write the next part that involves checking each different combination of cards. Recently having worked through python's itertools exercises on Hackerrank, the combinations functions was fresh in my mind.

While I was able to arrive at a solution that satisfied the test cases, I did not have time to think about the efficiency or Big O analysis of the problem.

There is obviously some refactoring that I could do to make things cleaner. With more time I would take an object oriented approach by making classes for cards and hands, and adding class methods to evaluate the hands.

For each round, we have to run check_hand() on each hand combination. Let's think about how many hands we have to evaluate:

We have to consider combinations of cards formed by taking out groups of 0, 1, 2, 3, 4 and 5 cards and adding the next number of cards in the deck that bring the total card count to 5, which means we have to do 5C0 + 5C1 + 5C2 + 5C3 + 5C4 + 5C5 calls to check_hand(). So the sum of total calls is 1 + 5 + 10 + 10 + 5 + 1 = 32.

For each of these 32 calls that happen when we run play(), check_hands() runs through each of the check_ functions starting with the highest value hand. As soon as it finds a 'match', check_hands() returns a number value (hand_value) corresponding to straight flush, four of a kind, etc. This value is then compared with the highest value that has been previously found (best_hand) and replaces that value if the current hand's hand rank has a higher value.

I'm not sure if there is faster way to find the best hand than the brute force method I implemented.