C Program for Animated Solution of Tower of Hanoi Puzzle Problem

This is a c program to solve towers of Hanoi puzzle problem with graphical demonstration. This c program demonstrates solution for tower of Hanoi puzzle with given number of disks. Tower of Hanoi is a mathematical game or puzzle. It is also called tower of Brahma or Lucas' tower. There are three towers (or rods) and a number of disks of different diameters. The program lets you enter the number of disks. As the number of disks increase, the difficulty of puzzle also increase. The disks have hole at center so that it can slide on to the rods. Initially all disks are stacked on the first tower, say tower A, such that no disk is placed over a smaller disk. To win the puzzle you have to move all those disks from tower A (first tower) to tower C (third tower). But there are a few rules to solve the puzzle. They are:

1. Only one disk can be taken at a time.
2. It is not allowed to take any disk other the topmost one from a tower.
3. Never place a larger disk on top of a smaller one.
4. Place a disk nowhere else other than on a tower.

This C program lets you select the number of disks (difficulty of puzzle) and demonstrates the optimal solution for the towers of Hanoi puzzle via animation. You can enter the number of disks when you start. The program solves the puzzle with minimum number of moves. The solving process is animated. For this purpose, we use the graphics library (graphics.h) in c. The solution is always optimal. For a 3 disks puzzle, the optimal number of moves is 7. This c program uses a recursive function to find the solution of tower of Hanoi puzzle. The program is as follows.

Output

#include<stdio.h>
#include<graphics.h>
#include<dos.h>
#include<math.h>

int tower[3][10];// the three towers' disks as stack
int top[3];//top of the three stacks
int from,to;//moving 'from' tower number 'to' tower number
int diskInAir;//number of disk moved (1 to n)
int l,b,u;

void push(int to, int diskno)
//putting disk on tower
{
tower[to-1][++top[to-1]]=diskno;
}

int pop(int from)
//take topmost disk from tower
{
return(tower[from-1][top[from-1]--]);
}

void drawStill()
{
int j,i,disk;
cleardevice();
for(j=1;j<=3;j++)
 {
 //draw tower
 setfillstyle(CLOSE_DOT_FILL,WHITE);
 bar(j*l,u,j*l+5,b);
 //draw all disks on tower
 for(i=0;i<=top[j-1];i++)
  {
  disk=tower[j-1][i];
  setfillstyle(SOLID_FILL,1+disk);
  bar(j*l-15-disk*5,b-(i+1)*10,j*l+5+15+disk*5,b-i*10);
  }
 }
}

void animator()
//to show the movement of disk
{
int x,y,dif,sign;
diskInAir=pop(from);
x=from*l;
y=b-(top[from-1]+1)*10;
//taking disk upward from the tower
for(;y>u-20;y-=15)
 {
 drawStill();
 setfillstyle(SOLID_FILL,1+diskInAir);
 bar(x-15-diskInAir*5,y-10,x+5+15+diskInAir*5,y);
 delay(100);
 }
y=u-20;
dif=to*l-x;
sign=dif/abs(dif);
//moving disk towards a target tower
for(;abs(x-to*l)>25;x+=sign*15)
 {
 drawStill();
 setfillstyle(SOLID_FILL,1+diskInAir);
 bar(x-15-diskInAir*5,y-10,x+5+15+diskInAir*5,y);
 delay(100);
 }
x=to*l;
//placing disk on a target tower
for(;y<b-(top[to-1]+1)*10;y+=15)
 {
 drawStill();
 setfillstyle(SOLID_FILL,1+diskInAir);
 bar(x-15-diskInAir*5,y-10,x+5+15+diskInAir*5,y);
 delay(100);
 }
push(to,diskInAir);
drawStill();
}

void moveTopN(int n, int a, int b, int c)
//Move top n disk from tower 'a' to tower 'c'
//tower 'b' used for swapping
{
if(n>=1)
 {
 moveTopN(n-1,a,c,b);
 drawStill();
 delay(1000);
 from=a;
 to=c;
 //animating the move
 animator();
 moveTopN(n-1,b,a,c);
 }
}

void main()
{
int i,gd=DETECT,gm,n;
printf("Enter number of disks");
scanf("%d",&n);
initgraph(&gd,&gm,"C:\\TURBOC3\\BGI\\");
//setting all tower empty
for(i=0;i<3;i++)
 {
 top[i]=-1;
 }
//putting all disks on tower 'a'
for(i=n;i>0;i--)
 {
 push(1,i);
 }
l=getmaxx()/4;
b=getmaxy()-50;
u=getmaxy()/3+100;
//start solving
moveTopN(n,1,2,3);
delay(4000);
getch();
}