Chapter - 9: Arrays

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. Draw the boxes. 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 the 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 aren’t 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 the 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 

This function gets the key from keyboard.

int getkey()
{
    int ch;
    ch = _getch();
    if (ch == 0)
    ch = _getch();
    return ch;
}

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

#define FALSE 0
#define TRUE 1

//scan codes for arrow keys.
#define UP 72
#define DOWN 80
#define LEFT 75
#define RIGHT 77

void gotoxy(short, short);
void box(short, short, short, short);
void update(short, short, short, short, int *a);
int getkey();
int check(int *a);
void action(int key, int a[4][4]);
void swap(int*, int*);

int main()
{
	int a[4][4] = {
		1, 4, 15, 7,
		8, 10, 2, 11,
		14, 3, 6, 13,
		12, 9, 5, 32
	};
	int key, flag = FALSE;

	gotoxy(30, 20);
	printf("\nArrange the numbes in ascending order.\nPress any key to start. . .");
	_getch();
	system("cls");//clrscr(); in TurboC++
	box(0, 0, 24, 8);
	while (flag == FALSE)//Game ends when flag becomes TRUE
	{
		update(0, 0, 24, 8, (int*)a);
		key = getkey();
		action(key, a);// It moves the numbers
		flag = check((int*)a);/*It make flag TRUE on completion of game*/
	}
	system("cls");
	gotoxy(30, 20);
	printf("\nYou've done it dude.!!\nExiting. . . ");
	_getch();
	_getch();
	return 0;
}

//It prints the numbers in the boxes.
void update(short x1, short y1, short x2, short y2, int *a)
{
	int i, j, num, k = 0;
	for (j = y1; j < y2; j++)//row
	{
		for (i = x1; i < x2; i++)//col
		{
			if (i > x1 && i < x2 && j > y1 && j < y2)
			{
				if ((i + 3) % 6 == 0 && j % 2 == 1)
				{
					gotoxy(i, j);
					num = a[k];
					if (num == 32)
						printf("  ");
					else
						printf("%d", num);
					k++;
				}
			}
		}
	}
}

//It draw box.
void box(short x1, short y1, short x2, short y2)
{
	int i, j;
	for (i = x1; i <= x2; i++) // col
	{
		for (j = y1; j <= y2; j++) //row
		{
			/*====printing corners========*/
			if (i == x1 && j == y1)
			{
				gotoxy(i, j);
				printf("%c", 218);
			}
			if (i == x2 && j == y1)
			{
				gotoxy(i, j);
				printf("%c", 191);
			}
			if (i == x1 && j == y2)
			{
				gotoxy(i, j);
				printf("%c", 192);
			}
			if (i == x2 && j == y2)
			{
				gotoxy(i, j);
				printf("%c", 217);
			}
			/*================================*/


			if (i < x2 && i > x1)
			{
				if ((i) % 6 == 0)//Vertical division coerners
				{
					if (j == y1)
					{
						gotoxy(i, j);
						printf("%c", 194); //T
					}
					if (j == y2)
					{
						gotoxy(i, j);
						printf("%c", 193);//Reverse T
					}
					if (j == y1 + 2 || j == y1 + 4 || j == y1 + 6)
					{
						gotoxy(i, j);
						printf("%c", 197);//+
					}
				}
				else if (j % 2 == 0)// Horizontal line
				{
					gotoxy(i, j);
					printf("%c", 196);
				}
			}



			if (j > y1 && j < y2)
			{
				if ((j % 2 == 0))
				{
					if (i == x1)
					{
						gotoxy(i, j);
						printf("%c", 195);//Rotate left T
					}
					if (i == x2)
					{
						gotoxy(i, j);
						printf("%c", 180);//Rotate right T
					}
				}
				else if (i % 6 == 0)
				{
					gotoxy(i, j);
					printf("%c", 179);//Vertical lines
				}
			}
		}
	}
}

//gotoxy in compilers other than TurboC++
void gotoxy(short col, short row)
{
	HANDLE h = GetStdHandle(STD_OUTPUT_HANDLE);
	COORD position = { col, row };
	SetConsoleCursorPosition(h, position);
}

int getkey()
{
	int ch;
	ch = _getch();
	if (ch == 0)
		ch = _getch();
	return ch;
}

//It check if the puzzle is solved or not.
int check(int *a)
{
	int i;
	for (i = 0; i < 15; i++)
		if (a[i] > a[i + 1])
			return FALSE;
	return TRUE;
}

//It moves the number.
void action(int key, int a[4][4])
{
	int i, j;
	for (i = 0; i < 4; i++)
		for (j = 0; j < 4; j++)
			if (a[i][j] == 32)
				goto BREAK;
BREAK:
	switch (key)
	{
	case RIGHT:
		if (j - 1 < 0) 
			return;
		swap(&a[i][j], &a[i][j - 1]);/*Moves the botton to right*/
		return;
	case DOWN:
		if (i - 1 < 0)
			return;
		swap(&a[i][j], &a[i - 1][j]);/*Moves the botton down*/
		return;
	case LEFT:
		if (j + 1 > 3)
			return;
		swap(&a[i][j], &a[i][j + 1]);/*Moves the botton left*/
		return;
	case UP:
		if (i + 1 > 3)
			return;
		swap(&a[i][j], &a[i + 1][j]);/*Moves the botton up*/
		return;
	default:
		return;
	}
}

void swap(int *a, int *b)
{
	int temp;
	temp = *a;
	*a = *b;
	*b = temp;
}

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