Thursday 18 September 2014

C++ program to reverse a linked list

C++ program to reverse a linked list using three pointers


C++ program to reverse a linked list

#include<iostream>
#include<conio.h>
using namespace std;
struct links
{
    int data;
    links *next;
};
class linkedlist
{
    links *start;
public:
    void create();
    void reverse();
    void display();
};
void linkedlist::reverse()
{
    links *temp1,*temp2,*temp3;
    temp1=start;
    temp2=NULL;
    while(temp1!=NULL)
    {
        temp3=temp2;
        temp2=temp1;
        temp1=temp1->next;
        temp2->next=temp3;
    }
    start=temp2;
}
void linkedlist::create()
{
    int take;
    links *temp;
    char ch;
    cout<<"Enter the element ";
    cin>>take;
    start=new links;
    start->data=take;
    start->next=NULL;
    temp=start;
    cout<<"Want to enter more elements (Y/N)\n";
    ch=getch();
    while(ch!='n'&&ch!='N')
    {
        cout<<"Enter the element ";
        cin>>take;
        temp->next=new links;
        temp=temp->next;
        temp->data=take;
        temp->next=NULL;
        cout<<"Want to enter more elements (Y/N)\n";
        ch=getch();
    }
}
void linkedlist::display()
{
    links *temp=start;
    while(temp!=NULL)
    {
        cout<<temp->data<<"-> ";
        temp=temp->next;
    }
    cout<<"NULL\n";
}
int main()
{
    linkedlist revert;
    cout<<"Create a list "<<endl;
    revert.create();
    cout<<"\nBefore reversing linked list\n ";
    revert.display();
    revert.reverse();
    cout<<"\nAfter reversing linked list\n";
    revert.display();
    return 0;
}

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