# Tower of Hanoi Program in C

#### Bygeekycodesco

Sep 6, 2021

Tower of Hanoi is a mathematical puzzle where we have three towers and n disks. The objective of the puzzle is to move the entire stack to another tower, obeying the following simple rules:

1. Only one disk can be moved at a time.
2. Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack.
3. No disk may be placed on top of a smaller disk.
##### Approach

Take an example for 2 disks : Let tower 1 = ‘A’, tower 2 = ‘B’, tower 3 = ‘C’.

Step 1 : Shift first disk from ‘A’ to ‘B’.

Step 2 : Shift second disk from ‘A’ to ‘C’.

Step 3 : Shift first disk from ‘B’ to ‘C’.

The pattern here is : Shift ‘n-1’ disks from ‘A’ to ‘B’. Shift last disk from ‘A’ to ‘C’. Shift ‘n-1’ disks from ‘B’ to ‘C’.

##### Sample

Input  − 3

Output   − A to B

A to C

B to C

A to B

C to A

C to B

A to B  Explanation − uses recursive function & solves the tower of Hanoi

##### Implementation of Hanoi Tower In C
```#include <stdio.h>

void towers(int, char, char, char);

int main()
{
int num;

printf("Enter the number of disks : ");
scanf("%d", &num);
printf("The sequence of moves involved in the Tower of Hanoi are :\n");
towers(num, 'A', 'C', 'B');
return 0;
}
void towers(int num, char frompeg, char topeg, char auxpeg)
{
if (num == 1)
{
printf("\n Move disk 1 from peg %c to peg %c", frompeg, topeg);
return;
}
towers(num - 1, frompeg, auxpeg, topeg);
printf("\n Move disk %d from peg %c to peg %c", num, frompeg, topeg);
towers(num - 1, auxpeg, topeg, frompeg);
}
```
##### Output
```Enter the number of disks : 3
The sequence of moves involved in the Tower of Hanoi are :

Move disk 1 from peg A to peg C
Move disk 2 from peg A to peg B
Move disk 1 from peg C to peg B
Move disk 3 from peg A to peg C
Move disk 1 from peg B to peg A
Move disk 2 from peg B to peg C
Move disk 1 from peg A to peg C```

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