Let Us C (Chapter 8 : Arrays) : Program-12

Very often in fairs we come across a puzzle that contains 15 numbered square pieces mounted on a frame. These pieces can be moved horizontally or vertically. A possible arrangement of these pieces is shown below: 

01     04     15     07 

08     10     02     11 

14     03     06     13 

12     09     05     Blank 

As you can see there is a blank at bottom right corner. Implement the following procedure through a program: Draw the boxes as shown above. Display the numbers in the above order. Allow the user to hit any of the arrow keys (up, down, left, or right). If user hits say, right arrow key then the piece with a number 5 should move to the right and blank should replace the original position of 5. Similarly, if down arrow key is hit, then 13 should move down and blank should replace the original position of 13. If left arrow key or up arrow key is hit then no action should be taken. The user would continue hitting the arrow keys till the numbers are not arranged in ascending order. Keep track of the number of moves in which the user manages to arrange the numbers in ascending order. The user who manages it in minimum number of moves is the one who wins. How do we tackle the arrow keys? We cannot receive them using scanf( ) function. Arrow keys are special keys which are identified by their scan codes. Use the following function in your program. It would return the scan code of the arrow key being hit. Don't worry about how this function is written. We are going to deal with it later. The scan codes for the arrow keys are: up arrow key – 72 down arrow key – 80 left arrow key – 75 right arrow key – 77

// Let Us C (Chapter 8 : Arrays) : Program-12
/* 
Very often in fairs we come across a puzzle that contains 15 numbered square
pieces mounted on a frame. These pieces can be moved horizontally or
vertically. A possible arrangement of these pieces is shown below: 
01	04	15	07
08	10	02	11
14	03	06	13
12	09	05	Blank

As you can see there is a blank at bottom right corner. Implement the
following procedure through a program: 
Draw the boxes as shown above. Display the numbers in the above order. Allow
the user to hit any of the arrow keys (up, down, left, or right). If user hits
say, right arrow key then the piece with a number 5 should move to the right
and blank should replace the original position of 5. Similarly, if down arrow
key is hit, then 13 should move down and blank should replace the original
position of 13. If left arrow key or up arrow key is hit then no action should
be taken. The user would continue hitting the arrow keys till the numbers
are not arranged in ascending order. Keep track of the number of moves in
which the user manages to arrange the numbers in ascending order. The user
who manages it in minimum number of moves is the one who wins.How do we
tackle the arrow keys? We cannot receive them using scanf( ) function. Arrow
keys are special keys which are identified by their scan codes. Use the
following function in your program. It would return the scan code of the
arrow key being hit. Don't worry about how this function is written. We are
going to deal with it later. The scan codes for the arrow keys are: 
up arrow key – 72 down arrow key – 80 left arrow key – 75 right arrow key – 77
*/

#include<stdio.h>
#include<conio.h>
#include<dos.h>

/* returns scan code of the key that has been hit */
getkey()
{
	union REGS i,o;
	while(!kbhit());
	i.h.ah=0;
	int86(22,&i,&o);
	return(o.h.ah);
}

void main()
{
	int i,j,a[16]={1,4,15,7,8,10,2,11,14,3,6,13,12,9,5,0};
	int temp,h,moves=0,won=0;
	clrscr();
	do{

		/**************/
		/* to move up */
		/**************/
		if(h==72)
		{
			for(i=0;i<16;i++)
			{
				if(a[i]==0)
				{
					if(a[0]==0 || a[1]==0 || a[2]==0 || a[3]==0)
					{
						break; // do nothing if space is on top rows
					}
					temp=a[i];
					a[i]=a[i-4]; // else copy content of top cell to down
					a[i-4]=temp; // move blank space down
					moves=moves+1;
					break;
				}
			}
		}

		/****************/
		/* to move left */
		/****************/
		if(h==75)
		{
			for(i=0;i<16;i++)
			{
				if(a[i]==0)
				{
					if(a[0]==0 || a[4]==0 || a[8]==0 || a[12]==0)
					{
						break;	// do nothing if space is at left edge
					}
					temp=a[i];
					a[i]=a[i-1];
					a[i-1]=temp;
					moves=moves+1;
					break;
				}
			}
		}

		/****************/
		/* to move down */
		/****************/
		if(h==80)
		{
			for(i=0;i<16;i++)
			{
				if(a[i]==0)
				{
					if(a[12]==0 || a[13]==0 || a[14]==0 || a[15]==0)
					{
						break; // do nothing if space is at bottom edge
					}
					temp=a[i];
					a[i]=a[i+4];
					a[i+4]=temp;
					moves=moves+1;
					break;
				}
			}
		}

		 /*****************/
		 /* to move right */
		 /*****************/
		if(h==77)
		{
			for(i=0;i<16;i++)
			{
				if(a[i]==0)
				{
					if(a[3]==0 || a[7]==0 || a[11]==0 || a[15]==0 )
					{
						break; // do nothing if space is at right edge
					}
					temp=a[i];
					a[i]=a[i+1];
					a[i+1]=temp;
					moves=moves+1;
					break;
				}
			}
		}

		/**********************************/
		/* printing the puzzle with boxes */
		/**********************************/
		printf("\n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c\n",218,196,196,196,194,196,
			196,196,194,196,196,196,194,196,196,196,191); // top content of box
		for(i=0;i<=15;i++)
		{
			printf("%c",179);	// print | before number
			if(a[i]==0)
			{
				printf("%c  ",32); // print blank space if number is zero
			}
			if(a[i]!=0)
				printf(" %2d",a[i]);	// print number with 2 indents
			if(a[i]==a[3] || a[i]==a[7] || a[i]==a[11] || a[i]==a[15])
				printf("%c",179);	// print last |
			if(i==3||i==7||i==11)
				printf("\n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c\n",195,196,196,196,197,
					196,196,196,197,196,196,196,197,196,196,196,180); // middle content of box
			if(a[0]==1 && a[1]==2 && a[2]==3 && a[3]==4 && a[4]==5 && a[5]==6 &&
				a[6]==7 && a[7]==8 && a[8]==9 && a[9]==10 && a[11]==12 && a[12]==13
				&& a[13]==14 && a[14]==15 && a[15]==0)	// required final position
			{
				won=1;
			}
		}
		printf("\n%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c%c\n",192,196,196,196,193,196,196,
			196,193,196,196,196,193,196,196,196,217);	// bottom content of box

		if(won==1)
		{
			printf("\n\n\tCongratulations! you have won.");
			break;
		}

		/**********************************/
		/* to print instructions for user */
		/**********************************/
		printf("\n\n\n\n\n\n Total Moves: %d\t\t\t\t Use arrow keys to move blank:\n\n",moves);
		printf("\t\t\t\t\t\t %c to move up\n",30);
		printf("\t\t\t\t\t\t %c to move down\n",31);
		printf("\t\t\t\t\t\t %c to move left\n",17);
		printf("\t\t\t\t\t\t %c to move right\n",16);


		/**********************/
		/* to take user input */
		/**********************/
		h=getkey();
		clrscr();
	}while(h==72 || h==75 || h==77 ||h==80);
	getch();
}

OUTPUT