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XI Olimpiad in Informatics 2003/2004

Task: zga

Guesswork

III stage competition, trial day  
Source file: zga.*
Memory limit: 32 MB

Alternative formats: PostScript PDF

Byteazar has became a chronic gambler. He throws away all money in the casino playing "guesswork". He purports it is possible to devise a game system that allows to beat the casino.

    A single game of guesswork consists in drawing consecutively 9 real numbers belonging to (0;1) using uniform distribution. Upon drawing each number the player must immediately guess the position of the number (with respect to greatness) among the 9 to be chosen. Obviously, it is not possible to forsee the position - one has to take a guess. If 9 positions have been correctly guessed, the player wins. Otherwise, the player loses. If, for instance, we describe the first drawn number as the second biggest and then draw two numbers smaller than it, we lose.

Task

Help Byteazar! Programme the best strategy for the guesswork you can. Write a programme which will play multiple games of guesswork, winning as many as possible. The higher the number of games won, the better evaluation of your programme will be. More precisely, for each game won the casino pays 423,99 byte-dollars to the player, for each lost it collects 13,53 byte-dollars from the player. Your programme shall play 10^6 games. The number of points you shall recieve will equal total profit divided by 10^4 and rounded to the closest integer within [0,100].
    You have to programme a module containing the following three procedures and functions:

  • procedure inicjalizuj / void inicjalizuj() (initialize in Polish) - this procedure shall be called only once, at the outset, before any game begins. You can use it to initialize your data structures.

  • procedure nowa_rozgrywka / void nowa_rozgrywka () (new_game in Polish) - this procedure will be called at the beginning of each game. You can use it to initialize the variables concerning a single game.

  • function kolejna_liczba (x : Double) : Integer / int kolejna_liczba (double x) (next_number in Polish) - this function recieves a drawn number x as a parameter, 0 < x < 1, with a precision of 12 decimal positions. The function should calculate the position of x among the 9 numbers drawn in this round and return the outcome. If the game is lost, the function may return any integer within [1,9].

Files (Pascal)


In the zga_pas directory you shall find the following files:

  • zga.pas - a frame of the game module containing empty procedures inicjalizuj, nowa_rozgrywka and function kolejna_liczba. You should write those procedures/functions.
  • kasyno.pas - a programme generating many (as many as it is indicated in the ILE_ZESTAWOW (number_of_games) constant) games of guesswork. Each game is played by means of the procedures and functions of the zga.pas game module. You can use this programme to test your game module.
  • makefile - this files makes it possible to compile the kasyno.pas programme with the game module zga.pas, using the make command.

Files (C/C++)


In the zga_c / zga_cpp directory you shall find the following files:
  • zga.h - a file containing headers of the functions: inicjalizuj, nowa_rozgrywka and kolejna_liczba.
  • zga.c / zga.cpp - a frame of the game module containing empty definitions of functions declared in the header file zga.h. You should write those functions.
  • kasyno.c / kasyno.cpp -a programme generating many (as many as it is indicated in the ILE_ZESTAWOW (number_of_games) constant) games of guesswork. Each game is played by means of the procedures and functions of the zga.c / zga.cpp game module. You can use this programme to test your game module.
  • makefile - this files makes it possible to compile the kasyno.c / kasyno.cpp programme with the game module zga.c / zga.cpp, using the make command.

Solution


The result of your work should consist of a single file: zga.c or zga.cpp or zga.pas.

Example


A hypothetical interaction between with programme could be as follows: (the numbers returned by the function kolejna_liczba are in italics; 2 games have been played):

Game 1

        0.043319026120
        1
        0.933801434041
        8
        0.992050359372
        9
        0.145189967093
        4
        0.518803250649
        6
        0.093583048537
        2
        0.764309529654
        7
        0.338653748790
        5
        0.119437652934
        3                   Victory
      

Game 2

0.164020610610 2 0.205594263575 3 0.042637391231 1 0.147521628974 1 Defeat 0.946549875333 1 0.772946216573 1 0.152956276544 1 0.539653928563 1 0.552047936535 1



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