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Learning Opportunities

This puzzle can be solved using the following concepts. Practice using these concepts and improve your skills.


This is a port of the Texas hold'em version of Poker.

The source code of this game is available on this GitHub repository.


The rules of Texas hold 'em can be found all over the web. For example : wikipedia with the hand ranking.

  Game parameters

The number of players may vary from 2 to 4 . The action moves clockwise around the table. The player 0 is at the top .

The total of all buy-ins is always $4800 . So for 2 players the buy-in is $2400 , for 3 players it's $1600 and for 4 players it's $1200 .

The value of the small blind / big blind are $5 / $10 . Then every 10 hands, the level will increase and the blinds (small and big) are multiplied by 2 (the first hand is 1 so to simplify the blinds will increase at hands 10 , 20 ,...).

The first big blind player is random.

These values are given as game inputs.

  End game

The game ends :
  • when one player owns all the chips.
  • after 600 rounds and if the last hand is not over, it's cancelled.

The players are ranked by elimination round and stack.


When a player timeouts :
  1. He is eliminated.
  2. He is considered folded for the current hand.
  3. The chips from his stack are removed from the game.


In heads-up :
  • Player 0 is on the left .
  • The dealer / button is the small blind.


The card's abbreviations are 2D , KH ... (complete list).

Hand examples AS_AD
Board examples X_X_X_X_X PREFLOP
Showdown examples   QH_3S_E_E_5C_H_7D_KC    player0's cards, followed by player1's cards ...
player1 was eliminated ( E ) at the start of the hand.


At the end of each hand, you will know the cards of all the players (even the folded ones).


  Possible actions

There are 5 possible actions / outputs :

  • CALL
  • BET amount , where amount is the number of chips that you add to the pot.
  • ALL-IN
  • FOLD

A list of all possible actions is given in your inputs. BET_240 means 240 is the minimum raise. You can bet more. If you bet less it will be replaced by CALL or BET 240 (depending on your amount).

In the inputs, BET actions have an underscore. In the outputs, you can use a space.

  Bet / Raise

A summary of some betting rules (with examples) can be found here .

  Action replacement

In some cases, if you give an "invalid" action, it will be automatically replaced by a "legal" one.

For example :

  • BET 500 with a stack of $400 will be replaced by ALL-IN .
  • TOTO or other invalid action will be replaced by FOLD .

However if you FOLD when you could just CHECK , it won't be replaced.

The replacement informations are written in the output console and a complete list can be found here .

  Other players actions

The actions of all the players are given as well as the round, hand's number, playerId and board cards when each action was done.

The action can be :

  • CALL
  • BET_500 , with an underscore after BET.
  • ALL-IN
  • FOLD
  • NONE , if no action during the hand (for example: if all players are directly all-in). Then playerId is -1 .
  • TIMEOUT , the player has timeout

The first action given is always your last action.


Only the big wins (more than 2 * BB * number of alive players) and level's changes are marked on the scrollbar.

There's a debug mode with "bigger" cards and buttons to show / hide the opponents cards and the folded cards.

The winning probabilities are calculated with a java version of kennethshackleton's SKPokerEval (a Texas Hold'em 7-card hand evaluator).

Victory Conditions
  • You own all the chips.
  • After 600 rounds you own the biggest stack.
Loss Conditions
  • You've lost all your chips.
  • You do not respond in time.

  Game Input

Initialization input
Line 1 : smallBlind
Line 2 : bigBlind the initial values of the blinds.
Line 3 : handNbByLevel number of hands to play to reach the next level.
Line 4 : levelBlindMultiplier blinds are multiply by this coefficient when the level changes.
Line 5 : buyIn initial stack for each player.
Line 6 : firstBigBlindId id of the first big blind player .
Line 7 : playerNb number of players ( 2 to 4 ).
Line 8 : playerId your id ( 0 to 3 ).

Input for one game turn
Line 1 : round (starts at 1 , game ends when it reaches 600 ).
Line 2 : handNb hand's number (starts at 1 ).
Next playerNb lines :
  • stack number of chips in the player's stack.
  • chipInPot number of player's chips in the pot. The sum of all the chipInPot values is equal to the pot.

Next line : boardCards board cards (example : AD_QH_2S_X_X ).
Next line : playerCards your cards (example : TC_JH ).
Next line : actionNb number of actions since your last turn.
Next actionNb lines :
  • actionRound round of the action.
  • actionHandNb hand number of the action.
  • actionPlayerId player id of the action ( -1 if action is NONE ).
  • action action (examples : BET_200 , FOLD , NONE ...).
  • actionBoardCards board cards when the action is done (example : AD_QH_2S_4H_X ).

Next line : showDownNb number of hands that ended since your last turn.
Next showDownNb lines :
  • showDownHandNb hand's number.
  • showDownBoardCards board cards at the showdown.
  • showDownPlayerCards players cards (example : QH_3S_E_E_5C_H_7D_KC player0's cards, followed by player1's cards ...).

Next line : possibleActionNb number of actions you can do.
Next possibleActionNb lines : possibleAction your possible action ( BET_240 means 240 is the minimum raise but you can bet more).

A single line containing the player action. Example: BET 200
You can also add a message : FOLD;MESSAGE
2 ≤ number of players ≤ 4
Response time first turn is ≤ 1000 ms.
Response time per turn is ≤ 50 ms.
1 ≤ round ≤ 600

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