Write a program to solve the Towers of Hanoi problem for a tower of size n, usin
ID: 3740803 • Letter: W
Question
Write a program to solve the Towers of Hanoi problem for a tower of size n, using both recursion and iteration. Time each method separately. Be very carefull to time only the actual work and avoid superfluous module calls and initialization, etc. Compare and contrast your two versions of the problem. Are they what you expected? Your analysis must contain a table of the times obtained for each run.
For a tower of a particular size, your output should consist of a list of moves that must be made as well as the times obtained. Disk 1 is always the top disk. Print your output to a file, not the screen. E.g. for a tower of size two Move disk 1 from tower A to tower C Move disk 2 from tower A to tower B Move disk 1 from tower C to tower B Run each version for the values n=1,2,3...50 or until you time out.
Explanation / Answer
############ Recursive ############
#include <stdio.h>
// C recursive function to solve tower of hanoi puzzle
void towerOfHanoi(int n, char from_rod, char to_rod, char aux_rod)
{
if (n == 1)
{
printf(" Move disk 1 from rod %c to rod %c", from_rod, to_rod);
return;
}
towerOfHanoi(n-1, from_rod, aux_rod, to_rod);
printf(" Move disk %d from rod %c to rod %c", n, from_rod, to_rod);
towerOfHanoi(n-1, aux_rod, to_rod, from_rod);
}
int main()
{
int n = 4; // Number of disks
towerOfHanoi(n, 'A', 'C', 'B'); // A, B and C are names of rods
return 0;
}
############### Iterative ############
// C Program for Iterative Tower of Hanoi
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <limits.h>
// A structure to represent a stack
struct Stack
{
unsigned capacity;
int top;
int *array;
};
// function to create a stack of given capacity.
struct Stack* createStack(unsigned capacity)
{
struct Stack* stack =
(struct Stack*) malloc(sizeof(struct Stack));
stack -> capacity = capacity;
stack -> top = -1;
stack -> array =
(int*) malloc(stack -> capacity * sizeof(int));
return stack;
}
// Stack is full when top is equal to the last index
int isFull(struct Stack* stack)
{
return (stack->top == stack->capacity - 1);
}
// Stack is empty when top is equal to -1
int isEmpty(struct Stack* stack)
{
return (stack->top == -1);
}
// Function to add an item to stack. It increases
// top by 1
void push(struct Stack *stack, int item)
{
if (isFull(stack))
return;
stack -> array[++stack -> top] = item;
}
// Function to remove an item from stack. It
// decreases top by 1
int pop(struct Stack* stack)
{
if (isEmpty(stack))
return INT_MIN;
return stack -> array[stack -> top--];
}
// Function to implement legal movement between
// two poles
void moveDisksBetweenTwoPoles(struct Stack *src,
struct Stack *dest, char s, char d)
{
int pole1TopDisk = pop(src);
int pole2TopDisk = pop(dest);
// When pole 1 is empty
if (pole1TopDisk == INT_MIN)
{
push(src, pole2TopDisk);
moveDisk(d, s, pole2TopDisk);
}
// When pole2 pole is empty
else if (pole2TopDisk == INT_MIN)
{
push(dest, pole1TopDisk);
moveDisk(s, d, pole1TopDisk);
}
// When top disk of pole1 > top disk of pole2
else if (pole1TopDisk > pole2TopDisk)
{
push(src, pole1TopDisk);
push(src, pole2TopDisk);
moveDisk(d, s, pole2TopDisk);
}
// When top disk of pole1 < top disk of pole2
else
{
push(dest, pole2TopDisk);
push(dest, pole1TopDisk);
moveDisk(s, d, pole1TopDisk);
}
}
//Function to show the movement of disks
void moveDisk(char fromPeg, char toPeg, int disk)
{
printf("Move the disk %d from '%c' to '%c' ",
disk, fromPeg, toPeg);
}
//Function to implement TOH puzzle
void tohIterative(int num_of_disks, struct Stack
*src, struct Stack *aux,
struct Stack *dest)
{
int i, total_num_of_moves;
char s = 'S', d = 'D', a = 'A';
//If number of disks is even, then interchange
//destination pole and auxiliary pole
if (num_of_disks % 2 == 0)
{
char temp = d;
d = a;
a = temp;
}
total_num_of_moves = pow(2, num_of_disks) - 1;
//Larger disks will be pushed first
for (i = num_of_disks; i >= 1; i--)
push(src, i);
for (i = 1; i <= total_num_of_moves; i++)
{
if (i % 3 == 1)
moveDisksBetweenTwoPoles(src, dest, s, d);
else if (i % 3 == 2)
moveDisksBetweenTwoPoles(src, aux, s, a);
else if (i % 3 == 0)
moveDisksBetweenTwoPoles(aux, dest, a, d);
}
}
// Driver Program
int main()
{
// Input: number of disks
unsigned num_of_disks = 3;
struct Stack *src, *dest, *aux;
// Create three stacks of size 'num_of_disks'
// to hold the disks
src = createStack(num_of_disks);
aux = createStack(num_of_disks);
dest = createStack(num_of_disks);
tohIterative(num_of_disks, src, aux, dest);
return 0;
}
YOu can change main method to run for particulat N value
#include <stdio.h>
// C recursive function to solve tower of hanoi puzzle
void towerOfHanoi(int n, char from_rod, char to_rod, char aux_rod)
{
if (n == 1)
{
printf(" Move disk 1 from rod %c to rod %c", from_rod, to_rod);
return;
}
towerOfHanoi(n-1, from_rod, aux_rod, to_rod);
printf(" Move disk %d from rod %c to rod %c", n, from_rod, to_rod);
towerOfHanoi(n-1, aux_rod, to_rod, from_rod);
}
int main()
{
int n = 4; // Number of disks
towerOfHanoi(n, 'A', 'C', 'B'); // A, B and C are names of rods
return 0;
}
############### Iterative ############
// C Program for Iterative Tower of Hanoi
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <limits.h>
// A structure to represent a stack
struct Stack
{
unsigned capacity;
int top;
int *array;
};
// function to create a stack of given capacity.
struct Stack* createStack(unsigned capacity)
{
struct Stack* stack =
(struct Stack*) malloc(sizeof(struct Stack));
stack -> capacity = capacity;
stack -> top = -1;
stack -> array =
(int*) malloc(stack -> capacity * sizeof(int));
return stack;
}
// Stack is full when top is equal to the last index
int isFull(struct Stack* stack)
{
return (stack->top == stack->capacity - 1);
}
// Stack is empty when top is equal to -1
int isEmpty(struct Stack* stack)
{
return (stack->top == -1);
}
// Function to add an item to stack. It increases
// top by 1
void push(struct Stack *stack, int item)
{
if (isFull(stack))
return;
stack -> array[++stack -> top] = item;
}
// Function to remove an item from stack. It
// decreases top by 1
int pop(struct Stack* stack)
{
if (isEmpty(stack))
return INT_MIN;
return stack -> array[stack -> top--];
}
// Function to implement legal movement between
// two poles
void moveDisksBetweenTwoPoles(struct Stack *src,
struct Stack *dest, char s, char d)
{
int pole1TopDisk = pop(src);
int pole2TopDisk = pop(dest);
// When pole 1 is empty
if (pole1TopDisk == INT_MIN)
{
push(src, pole2TopDisk);
moveDisk(d, s, pole2TopDisk);
}
// When pole2 pole is empty
else if (pole2TopDisk == INT_MIN)
{
push(dest, pole1TopDisk);
moveDisk(s, d, pole1TopDisk);
}
// When top disk of pole1 > top disk of pole2
else if (pole1TopDisk > pole2TopDisk)
{
push(src, pole1TopDisk);
push(src, pole2TopDisk);
moveDisk(d, s, pole2TopDisk);
}
// When top disk of pole1 < top disk of pole2
else
{
push(dest, pole2TopDisk);
push(dest, pole1TopDisk);
moveDisk(s, d, pole1TopDisk);
}
}
//Function to show the movement of disks
void moveDisk(char fromPeg, char toPeg, int disk)
{
printf("Move the disk %d from '%c' to '%c' ",
disk, fromPeg, toPeg);
}
//Function to implement TOH puzzle
void tohIterative(int num_of_disks, struct Stack
*src, struct Stack *aux,
struct Stack *dest)
{
int i, total_num_of_moves;
char s = 'S', d = 'D', a = 'A';
//If number of disks is even, then interchange
//destination pole and auxiliary pole
if (num_of_disks % 2 == 0)
{
char temp = d;
d = a;
a = temp;
}
total_num_of_moves = pow(2, num_of_disks) - 1;
//Larger disks will be pushed first
for (i = num_of_disks; i >= 1; i--)
push(src, i);
for (i = 1; i <= total_num_of_moves; i++)
{
if (i % 3 == 1)
moveDisksBetweenTwoPoles(src, dest, s, d);
else if (i % 3 == 2)
moveDisksBetweenTwoPoles(src, aux, s, a);
else if (i % 3 == 0)
moveDisksBetweenTwoPoles(aux, dest, a, d);
}
}
// Driver Program
int main()
{
// Input: number of disks
unsigned num_of_disks = 3;
struct Stack *src, *dest, *aux;
// Create three stacks of size 'num_of_disks'
// to hold the disks
src = createStack(num_of_disks);
aux = createStack(num_of_disks);
dest = createStack(num_of_disks);
tohIterative(num_of_disks, src, aux, dest);
return 0;
}
YOu can change main method to run for particulat N value
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