newbe needs some help

newbe needs some help sodoku puzzle

Hello all. I am taking my first class in C and have a professor thats all about having you learn on your own. Anyway Im trying to write a solution to the Sodoku puzzle. What I dont know is how to scan a row for a number that I am trying to enter. professor says I should use an index. I have no clue how to set that up. Here is the part that Where I set up the initial puzzle

Code:

void getGivens(struct sudoCell grid[9][9]) /* User enters starting pattern */ { int row, col, digit; char instring[50]; printf("Enter Sudoku pattern line by line.\n"); printf("Enter \'0\' for each undetermined cell\n"); printf("Enter a digit 1..9 followed by a space for each starting cell\n"); for (row=0; row<9; ++row) { /* Users dont understand rows numbered 0 */ printf("Enter row %d: ", row+1); fgets(instring, sizeof(instring), stdin); sscanf(instring, "%d %d %d %d %d %d %d %d %d", &grid[row][0].digit, &grid[row][1].digit, &grid[row][2].digit, &grid[row][3].digit, &grid[row][4].digit, &grid[row][5].digit, &grid[row][6].digit, &grid[row][7].digit, &grid[row][8].digit); for (col=0; col<9; ++col) grid[row][col].given = grid[row][col].digit>0; } return; }

There is a few ways you could do this with arrays. You could try a 9 x 9 2 Dimensional array or if you're up for it, you could probably make it more efficient with a 3 Dimensional of 3 x 3 x 9. Visually you're options would look something like this:

Code:

2D Array [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] [ ][ ][ ][ ][ ][ ][ ][ ][ ] 3D Array [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] --------- --------- --------- [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] 0 1 2 [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] 3 4 5 [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] 6 7 8 --------- --------- --------- [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ] [ ][ ][ ]|[ ][ ][ ]|[ ][ ][ ]

Essentially, the 3D array will break your array down into the managable 3 x 3 boxes. You just have to make sure you have each of these placed correctly. Something like how I have displayed to the right. This way you can do your checks based on the third index (each three by three box) and the same values of the first, for each 3 set of indexes ( array[0][0][0], array[0][0][1], array[0][0][2] ).

Which of these two you choose is up to you, but personally, I think the latter would make the 3 x 3 box more visually appealing. Now how you display this on the screen could be tougher. Your best bet would be to output the array right at the beginning, then prompt a user for a move. Whenever a move is made, place it into the cooresponding array spot, clear the screen and output the array again. Do this until the puzzle is finished. :)

thanks for the reply. to display the board I used the CP437 from wikipedia works great

Code:

╔═══╤═══╤═══╦═══╤═══╤═══╦═══╤═══╤═══╗ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╠═══╪═══╪═══╢═══╪═══╪═══╢═══╪═══╪═══╣ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╠═══╪═══╪═══╢═══╪═══╪═══╢═══╪═══╪═══╣ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╟───┼───┼───╫───┼───┼───╫───┼───┼───╢ ║ 1 │ 2 │ 3 ║ 4 │ 5 │ 6 ║ 7 │ 8 │ 9 ║ ╚═══╧═══╧═══╩═══╧═══╧═══╩═══╧═══╧═══╝

so if I convert it to a 3 dimensional array and start with the first cell.
I want to put a 1 in it but have to make sure that row 1 and col 1 do not already contain a 1 I would use an if statement with an equivalent test (== "1") right?

Your user would input something similar to this:

Code:

Input the following ( Row, Column, Value ): 5 7 8

With that user input, create your algorithm to convert this to your array index, which would be array[0][1][5] (if you use the 3D array), after that you check to see if that has ANY value in it that isn't zero. If it's already filled, you could either produce an error message or you could prompt the user if they wish to replace the box, it's up to use. If it doesn't have anything in it, you fill it with the value. Then you move onto the part of the code that checks to see if the puzzle is complete.

Nice grid by the way, were you able to output those non-standard characters in your program?

I wouldn't use a 3D array. It's way too complicated checking rows and columns that way. Much easier to use simple math on the row and column to check the 3x3 grid the entered coordinate falls in.

Quzah.

I have a function to have the user enter input. not sure if it is any good.
Im a little sketchy about 3d arrays like I said Im very new to this perhaps if I post everything that I have you can help me work with what I have I dont want to get too far out of my means Im like a third grader when it comes to programming. ;)

Code:

#include <stdio.h> /* Data declarations */ struct sudoCell { int digit; int given; }; /* Function declarations */ void getGivens(struct sudoCell[9][9]); /* User enters starting grid */ void sudoPrint(struct sudoCell[9][9]); /* Print current state */ int sudoSolver(struct sudoCell[9][9]); /* Sudoku solver */ int main() { int row, col, digit; struct sudoCell grid[9][9]; /* Sudoku grid */ /* Get starting grid pattern fom user */ getGivens(grid); /* Get starting pattern */ sudoPrint(grid); /*Print starting pattern */ /* Call solver for Sudoku pattern */ while (sudoSolver(grid)) { sudoPrint(grid); getchar(); } printf("That's all folks\n"); getchar(); return 0; } void getGivens(struct sudoCell grid[9][9]) /* User enters starting pattern */ { int row, col, digit; char instring[50]; printf("Enter Sudoku pattern line by line.\n"); printf("Enter \'0\' for each undetermined cell\n"); printf("Enter a digit 1..9 followed by a space for each starting cell\n"); for (row=0; row<9; ++row) { /* Users dont understand rows numbered 0 */ printf("Enter row %d: ", row+1); fgets(instring, sizeof(instring), stdin); sscanf(instring, "%d %d %d %d %d %d %d %d %d", &grid[row][0].digit, &grid[row][1].digit, &grid[row][2].digit, &grid[row][3].digit, &grid[row][4].digit, &grid[row][5].digit, &grid[row][6].digit, &grid[row][7].digit, &grid[row][8].digit); for (col=0; col<9; ++col) grid[row][col].given = grid[row][col].digit>0; } return; } void sudoPrint(struct sudoCell grid[9][9]) /* Print grid */ { /* Line drawing characters from code page 437 */ const char SP = ' '; const char HB = 0xC4; const char VB = 0xB3; const char CRS = 0xC5; const char DVB = 0xBA; const char DHB = 0xCD; const char DLL = 0xC8; const char DLR = 0xBC; const char DUL = 0xC9; const char DUR = 0xBB; const char DLT = 0xCC; const char DRT = 0xB9; const char DTT = 0xCB; const char DBT = 0xCA; const char DCR = 0xB6; const char DLST = 0xC7; const char DRST = 0xB6; const char DTST = 0xD1; const char DBST = 0xCF; const char DVSB = 0xD7; const char DHSB = 0xD8; int row, col; char ch; /* Top Border */ printf("%c", DUL); for (col=0;col<8; ++col) if (col%3 !=2) printf("%c%c%c%c", DHB, DHB, DHB, DTST); else printf("%c%c%c%c", DHB, DHB, DHB, DTT); printf("%c%c%c%c\n", DHB, DHB, DHB, DUR); /* Rows */ for (row=0; row<9; ++row) { /* Data Row */ printf("%c", DVB); for (col=0; col<9; ++col) { if (grid[row][col].digit == 0) ch = SP; else ch = grid[row][col].digit+'0'; if (col%3 !=2) printf("%c%c%c%c", SP, ch, SP, VB); else printf("%c%c%c%c", SP, ch, SP, DVB); } printf("\n"); /* Border below data row */ if (row<8) { if (row%3 !=2) printf("%c", DLST); else printf("%c", DLT); for (col=0; col<8; ++col) { if (row%3 != 2) printf("%c%c%c", HB, HB, HB); else printf("%c%c%c", DHB, DHB, DHB); if (col%3 != 2) if (row%3 != 2) printf("%c", CRS); else printf("%c", DHSB); else if (row%3 != 2) printf("%c", DVSB); else printf("%c", DCR); } if (row%3 != 2) printf("%c%c%c%c\n", HB, HB, HB, DRST); else printf("%c%c%c%c\n", DHB, DHB, DHB, DRT); } } /* Bottom border */ printf("%c", DLL); for (col=0; col<8; ++col) if (col%3 != 2) printf("%c%c%c%c", DHB, DHB, DHB, DBST); else printf("%c%c%c%c", DHB, DHB, DHB, DBT); printf("%c%c%c%c\n", DHB, DHB, DHB, DLR); return; } /* Solver for Sudoku grid */ int sudoSolver(struct sudoCell grid[9][9]) { return 0; /* for the time being until I figure you out */ }

now I have to test the first cell for anything in it I imagine with a if statement maybe if(grid[0][0].digit == '\0')
then test for a 1 existing in the row I thought
if(grid[row][0] == "1")
but these dont work what am I doing wrong

It's really your preference with the 2D array or 3D array. Either way you choose, one thing is gonna be nice and easy to check and the other will require some math. For me, I can visualize it better with a 3D array, but Quzah likes 2D. You seemed to have already implemented a 2D array, so I would just go with that, there is no point in changing it now.

As of the way your program looks now, it's a real nice program that could output a pretty nice looking completed soduku puzzle. :)

One thing I noticed is that you didn't intialize your array values which gives you some pretty funky looking results if you don't complete the input (Try one number for each row). Other than that, you look like you're in pretty good shape to start implementing the game part. There's plenty of ways to do it, so give it an attempt, and if you're having trouble, just post your attempt.

now I have to test the first cell for anything in it I imagine with a if statement maybe if(grid[0][0].digit == '\0')
then test for a 1 existing in the row I thought
if(grid[row][0] == "1")
but these dont even compile and every variation seems seems to be wrong but I cant think of anything else.

What are your errors? Most likely I'd expect a problem with this:

if(grid[row][0] == "1")

because there is a big difference between "1" and '1'.

(grid[row][0] == "1")
invalid operands to binary ==

(grid[row][0] == '1')
invalid operands to binary ==

also Im writing this on Dev-C++ (also writes c programs)
with their compiler
not borlands compiler.

Show me the code for that part.

Code:

/* Solver for Sudoku grid */ int sudoSolver(struct sudoCell grid[9][9]) { int row, col; if(grid[row][0] == "1") { if(grid[0][col] == "1")return 0; else printf("not working"); } else printf("not working"); }

my plan was to start with this and input a 1 in the first cell and if everything runs without the message "not working" I could continue on but i keep getting the error
"invalid operands to binary =="

That's because grid[][] is not a value, but grid[][].digit is. I also noticed that if your indexed value doesn't have it's expected "1", it gets trapped in the function forever.

wow cant believe I missed that thx thats when you know you have been staring at the same piece of code for too long
now by changing that I am attempting to compare an integer with a pointer and the compiler will give me a warning and the program will terminate without finishing. And thats the problem I had when I first came on the message board -- how can I change "1" to a pointer?

Essentially, it is a pointer to a string literal that's placed into memory when the program is run. When it's compiled, it makes all those literals into constant strings to be put into memory and replaces them in the code with pointers to that memory. At least, I think that's what it does. :confused:

In cases like this, you're supposed to convert the value to it's address, not the other way around. :)

For me, I'm not getting that error. I'm also doing this on Dev-C++.

Is your code like this?

Code:

int sudoSolver(struct sudoCell grid[9][9]) { int row, col; if(grid[row][0].digit == "1") { if(grid[0][col].digit == "1") return 0; else printf("not working"); } else printf("not working"); }

thats exacly what I have-- the compiler didnt even give you a warning.
mine says
[Warning]comparison between pointer and integer

it will let me run the program but right after it prints out the table a windows pop-up says the program encountered an error and must close.

I'll try what you suggested I'm not sure how butthank god I have a 4 day weekend and a ton of coffee.

Just frustrating paying a college for a professor who would rather you learn on your own that him teaching, and no money to go to a different college. :mad:

Do you know of any other sites with some good c tutorials seems most are converting to c#.

Yes, I get the warning, but it doesn't close it. Go back to what I said before though. :)

There is a big difference between "1" and '1' and, in this case it matters, 1.

:)

thx so much it's hard to find someone that will actually help instead of make fun of you when you ask a question.

I got rid of the warning my program will still get a windows error but at least I know its not the compiler anymore, maybe my Dev-C++ program
important thing is I can finish my code now

just out of curiosity I am a second year student do you think I am far behind and making mistakes that I should know by now. and have a lot of ground to make up. or right where I should be. :confused:

I have written a Sudoku solver that solves thousands of Sudoku problems in a fraction of a second and I use a single dimensional vector, i.e.,

Code:

T s[ 81 ];

I have a tip. First figure out the algorithm to solve a Sudoku grid efficiently, and after that you define the data (of type T that I defined above) to use. Do the algorithm by hand on paper. Here is a good link that may give you idéas for your algorithm: http://www.sudokusolver.co.uk/
Good luck!