Thread: Mastermind C project, need help!

Hello guys, its my first thread on this forum.

I got project from computer programming which is game mastermind. For those who dont know this game the point is to guess secret code which is set by one of the players. For example player set up secret code which is 4 integer numbers in range from 0 - 5, he can reapet number but can't leave empty spaces between them. The second player have to guess the sequence of the code.
So, for example code is 0 1 2 1
second player make random guess 0 0 1 1, of course it would be almost impossible to guess the sequence without any tips so, after each made guess player who create the code give guessing player answer, how many of the numbers is placed on correctly, or how many of the numbers is in the sequence but its place is wrong. So if the code was 0 3 2 1 and player made a guess 0 0 1 1 his answer will be 2 - are placed correctly and 1 - is in the code but on the wrong placed.


Now moving to the point after basic ideas of the game, i have to write a programm which will guess the sequence basing only on the answers. So the user write down or imagine some code of 4 integere numbers in range from 0 - 5, and programm starts guessing, after each guess user gives the answers until computer will break the code.


Generally i got problem with everything i dont have idea even how to start it, i am real beginner about programming and espacialy about the C language. Any ideas how to make algorithm some parts of the code in general would be helpful. Thanks for your time!

The very first thing you do is put your computer aside, get some paper and a pen, and begin planning how you want to approach this.

Think about the logic you will need to solve this problem. Figure out the list of steps you must follow in order to solve this problem "on paper". When you have a list of steps, then you can start converting it into code.

Programming is about problem-solving. Working through these steps to come up with an algorithm on your own is an important skill to learn.

Start thinking of how you might go about solving this problem "by hand", and see what you come up with.

So, i've been working on it for a while. I followed your suggestion and i made something and got some ideas, but i am writing here again cause i need your help about ideas how i can implement this.
So i got an array with 1296 elements which contains all combinations with number numbers from 1 - 6.
Now i am working on algorithm which will solve this dependly on answer, my idea is that it will delete combinations from an array which will give him the same answer as previous guesses. and delete all combinations with some number if it is sure that this number cannot be contained in the secret code.

I am surprised that you were asked to program the "code breaker", and not the "code maker".

Anyway, I would first think about how to organize the data involved. I would handle each code digit individually rather than combined into a single 4 digit integer value.

So you might use several four element arrays - one array for the code, one array for the guess, and one array to hold the status of each digit in the guess (correct in value and location, correct in value only, undetermined).

Simply striking all combinations that would produce the same clues (answers) as in previous guesses will not work though. Since you (the program) do not know the code, you also do not know what the answer would be for any other combination.

-

The idea is to start with a set of all possible combinations.

LOOP:

Randomly chose a guess from the set of possible combinations.
Remove guess from set.

Note the score the guess gets.
If it's a winning score, end loop

Compare the guess against all remaining possibilities.
If a possibility doesn't get the same score, remove it from the set.

ENDLOOP

This algorithm is not optimal, but will solve the problem.
For optimality, see Knuth's algorithm (and refinements).

As for maintaining the set, you only need a single bit per member.
So for 1296 numbers, you need a 1296/8 = 162 byte bit array.

Originally Posted by algorism

...
Compare the guess against all remaining possibilities.
If a possibility doesn't get the same score, remove it from the set.
...

That makes more sense.

-

Originally Posted by algorism

The idea is to start with a set of all possible combinations.

LOOP:

Randomly chose a guess from the set of possible combinations.
Remove guess from set.

Note the score the guess gets.
If it's a winning score, end loop

Compare the guess against all remaining possibilities.
If a possibility doesn't get the same score, remove it from the set.

ENDLOOP

This algorithm is not optimal, but will solve the problem.
For optimality, see Knuth's algorithm (and refinements).

As for maintaining the set, you only need a single bit per member.
So for 1296 numbers, you need a 1296/8 = 162 byte bit array.

Ok, so i got problems about implementing this to my programm, any ideas or suggestions how can i do it? I mean this algorithm which will compare the answers and remove possibilites from an array.

Hey, guys i've been working on for a while. And i completly got stuck in this moment, and the deadline is coming for me.

Code:

#include <stdio.h>
#include <time.h>
#include <cstdlib>
#include <string.h>


using namespace std;


char allseq[1296][4];
int z;
void hit_counter(char *seq_1, char *seq_2, int *result_1, int *result_2);


void sequence_deleter(char *seq);




int main() {
	srand((unsigned)time(NULL));
	int round/* z */, x, y, c, p;
	char code[5];
	char str[5];
	//char allseq [1926][4];
	int  sl, sk, skl;											//sl-s³owo ³amacz
	z = 1296;
	//sk-s³owo koder
	//skl-s³owo klucz
	for (x = 0; x<1296; x++)
	{


		allseq[x][0] = (x % 6) + 1;
		allseq[x][1] = ((x / 6) % 6) + 1;
		allseq[x][2] = ((x / 36) % 6) + 1;
		allseq[x][3] = ((x / 216) % 6) + 1;


	};
	x = rand() % z;
	sl = allseq[x][3] * 1000 + allseq[x][2] * 100 + allseq[x][1] * 10 + allseq[x][0];
	printf("First guess: ");
	printf("%d", sl);
	printf("\nAnswer: ");
	scanf("%4s", code);
	sprintf(str,"%d",sl);
	int k=0;
	int number_x = 0;
	int number_o = 0;
	while (code[k])
	{
		if (code[k] == 'x')
		{
			number_x++;
			k++;
			continue;
		}
		else if (code[k] == 'o')
		{
			number_o++;
			k++;
			continue;
		}
		k++;
	}
	int res1, res2;
	for (int i = 0; i < 1296;i++)
	{
		hit_counter(allseq[i], str, &res1, &res2);
		if (res1 != number_x || res2 != number_o)
		{ sequence_deleter(allseq[i]); }
	}


	system("pause");
	return 0;
}




void hit_counter(char *seq_1, char *seq_2, int *result_1, int *result_2)   {
	char k1[5];  /* for sequence copy not to destroy the original one */
	*result_1 = 0; /* for good placed pin's black one's) */
	*result_2 = 0; /* for white pin's */


	strcpy(k1, seq_1);
	for (int i = 0; i < 4; i++)
	{
		if (k1[i] == seq_2[i])
		{
			*result_1++;
			k1[i] = 'S';
		}
	}


	for (int i = 0; i < 5; i++)
	{
		for (int j = 0; j < 4; j++)
		{
			if (k1[i] == seq_2[j])
			{
				*result_2++;
				k1[i] = 'S';
			}


		}
	}
}




void sequence_deleter(char *seq)
{
	int i=0;
	while (seq[i])
	{
		seq[i] = 'S';
	}
}

Here is my code, generally i have no idea how to move on. I dont know how it should cope my strings and delete them from the all_seq two dimensional array. Generally i don't know how to send all these sequence combination to these functions. Any idea how i can finish this or something useful? Looking forward for your quick answers, thanks for all help to this time!

This is supposed to be C, right? Because "<cstdlib>" and "using namespace std" are C++.

Yes, yes. Only C, forget to remove this library from the beginning, my compilator just added it

What compiler/IDE are you using? It's not good that it adds such things. Are you compiling as C?

Yes i'm compiling as C, and its working.

Originally Posted by gugi10

Yes i'm compiling as C, and its working.

There is no C compiler I am aware of that automatically adds C++ statements to the code by itself. But since you don't seem to care enough to provide more information, then I don't care either.

Your code is very difficult to follow. Quite frankly, it's a mess.

• There is a lot of clutter
• Multiple unused variables
• Poor variable naming (single-letter and unclear variable names)
• Poor variable usage (global variables, redundant variables that serve the same purpose)
• Use of magic numbers all over the place

It appears you banged out code as you went, instead of planning the program (like I originally suggested) and testing along the way.

When I tried to run the program (guessing what the input should be based on the code), it seg-faulted.

I don't think I can personally help you salvage this.