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#include <iostream>
using namespace std;
int generateAnswer();
void trim (int guesses[], int guess, int &length, int black, int white);
void evaluate( int guess, int answer, int &black, int &white);
int nthDigit( int combination, int position ); // identify a digit
void clearNthDigit( int &combination, int position ); // clear a digit
int methodicalEliminate (int answer);
char play;
char response;
int answer;
const int size = 4096;
int main() // Plays the game
{
play = 'y';
while (play == 'y')
{
int answer = generateAnswer();
cout<<"It took methodicalEliminate "<< methodicalEliminate(answer)<<" tries";
cout<<"Would you like to plasy Mastermind? ";
cin >> play;
}
return 0;
}
int generateAnswer()
/*
Either lets the user at the keyboard choose the mystery combination,
or gives the option to have the computer generate a random combination.
*/
{
cout<<"Do you want to create the mystery combination? Respond with y for yes or n for computer."<<endl;
cin>>response;
if(response=='y'){
cout<<"Enter your combination.(4 digits ranging from 1-8.)"<<endl;
cin>>answer;
}
else{
answer=1000*(1+rand()%8)+100*(1+rand()%8)+10*(1+rand()%8)+1*(1+rand()%8);
cout<<"The combination that is trying to be guessed is "<<answer;
}
return answer;
}
int generateSearchSpace(int guesses[], int& length)
/*
Populates an array with all possible combinations of four-digit
values in the range 1 to 8.
*/
{
int a = 0;
for (int b = 1; b <=8; b++)
for (int c = 1; c <=8; c++)
for (int d = 1; d <= 8; d++)
for (int e = 1; e <=8; e++)
{
guesses[a] = 1000*b + 100*c + 10*d + 1*e;
a++;
}
return length = a;
}
void trim (int guesses[], int guess, int &length, int black, int white)
/*
Trim function analyzes the response to a particular guess and then eliminates
any values from the list of possibilities that are no longer
possible answers.
*/
{
int newLength = 0;
int trimBlack = 0;
int trimWhite = 0;
for(int i = 0; i < length; i++)
{
evaluate(guesses[i], guess, trimBlack, trimWhite);
if(trimBlack==black&&trimWhite==white) // If they are matched, keep them because one of them could be the right answer.
{
guesses[newLength]=guesses[i];
newLength++;
}
length=newLength;
}
}
int methodicalEliminate (int answer)
/*
beginning with a list of all possible candidate answers
continually guesses the first element in the list, and
trim answers accordingly, until an answer is found
*/
{
int guesses[size];
int length = 0;
int black = 0;
int white = 0;
int count = 0;
int currentGuess;
generateSearchSpace(guesses, length);
while(black< 4)
{
currentGuess=guesses[0];
evaluate(currentGuess,answer,black,white);
for(int i = 0; i < length; i++)
{
trim(guesses, currentGuess, length, black, white);
}
count++;
}
return count; // returns how many times did this function take to guess the right answer.
}
void evaluate( int guess, int answer, int &black, int &white )
/*
evaluates a combination by comparing it with the answer
Correctness is indicated by black pegs (correct digit in correct position)
and white pegs (correct digit in incorrect position)
*/
{
black = 0;
white = 0;
for (int i=1; i<=4; i++)
if (nthDigit( guess, i ) == nthDigit( answer, i ) )
{
black++;
clearNthDigit( guess, i );
clearNthDigit( answer, i );
}
for (int i=1; i<=4; i++)
for (int j=1; j<=4 && nthDigit(guess,i)>0; j++)
if (nthDigit( guess,i ) == nthDigit( answer, j ) )
{
white++;
clearNthDigit( guess, i );
clearNthDigit( answer, j );
}
}
int nthDigit( int combination, int position )
/*
identified the n'th digit of a combination
*/
{
int current;
while (position < 4)
{
combination /= 10;
position++;
}
return (combination % 10);
}
void clearNthDigit( int &combination, int position )
/*
clears the n'th digit of a combination to zero, so it will no longer match
digits must be counted in the same manner as nthDigit above.
*/
{
int current; // position currently being examined
int digitValue;
current = 4;
digitValue = 1;
while (position < current)
{
digitValue *= 10; // previou digit has 10 times the value
current--; // digitValue refers to previous digit
}
// subtract the digit minus itself to make it into a zero digit
combination -= digitValue * nthDigit( combination, position );
}
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