C Programming Code Examples
C > Data Structures Code Examples
Reversal of a singly linklist by recursion
/* Reversal of a singly linklist by recursion */
#include<stdio.h>
#include<conio.h>
#include<alloc.h>
struct node
{
int data;
struct node*next;
};
void insert(struct node**p,int num) /*Function for inserting an
element into a list */
{
if(*p==NULL)
{
(*p)=(struct node*)malloc(sizeof(struct node));
(*p)->next=NULL;
(*p)->data=num;
}
else
{
insert(&((*p)->next),num);
}
}
void display(struct node*p) /*Function for displaying the list*/
{
while(p!=NULL)
{
printf("%d ",p->data);
p=p->next;
}
}
void reverse(struct node**p) /*Function for reversing the list by
recursion */
{
struct node*q,*r,*x;
int d;
q=(*p); /*stores the address of the first element */
x=q; /*also stores the element of the first element for
counter pourpose */
d=q->data; /*stores the data of the first element*/
r=q->next; /*stores the address of the second element in the list
*/
free(q); /*deletes the first element of the list*/
if(x==NULL)
return ;
else
{
reverse(&(r));/*Recursive call*/
insert(p,d); /*This function is put in the stack so the first
will be taken as last element for the new list */
}
}
void main()
{
clrscr();
struct node*p=NULL;
int n,d,i=0;
printf("How many...? ");
scanf("%d",&n);
while(i++!=n)
{
scanf("%d",&d);
insert(&p,d);
}
display(p);
reverse(&p);
printf("
The reversed list is...");
display(p);
getch();
}
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