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reverseLinkedList.cpp
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reverseLinkedList.cpp
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#include<bits/stdc++.h>
using namespace std;
class node {
public:
int data;
node* next;
};
void insertAtHead(node* &head,int n)
{
node* newNode = new node();
newNode->data = n;
newNode->next = head;
head = newNode;
}
void printList(node* head)
{
node* temp = head;
while(temp!=NULL)
{
cout<<temp->data<<" ";
temp = temp->next;
}cout<<endl;
}
//reverse linkedlist iteratively
void reverse(node* &head)
{
node *currptr = head, *prevptr = NULL, *nextptr = NULL;
while(currptr!=NULL)
{
nextptr = currptr->next;
currptr->next=prevptr;
prevptr = currptr;
currptr = nextptr;
}
head = prevptr;
}
//reverse linkedlist recursively
node* recRevLink(node* &head)
{
if(head==NULL||head->next==NULL)
{
return head;
}
node* newHead = recRevLink(head->next);
head->next->next=head;
head->next=NULL;
return newHead;
}
int main()
{
node* head = NULL;
insertAtHead(head,6);
insertAtHead(head,3);
insertAtHead(head,5);
insertAtHead(head,2);
printList(head);
// reverse(head);
node* newHead = recRevLink(head);
printList(newHead);
}