week7-1b.c

#include <stdio.h>

struct node{
    int data;
    struct node * next;
};

struct node * newnode(int value){
    struct node * temp=(struct node*)malloc(sizeof(struct node));
    temp->data=value;
    temp->next=NULL;
    return temp;
}

void InsertAtBeg(struct node ** head,int x){
    struct node * temp=newnode(x);
    temp->next=*head;
    *head=temp;
}

void InsertAtEnd(struct node ** head,int x){
    struct node *temp=newnode(x);
    if(*head==NULL){
        *head=temp;
    }
    else{
        struct node * Lastnode=*head;
        while(Lastnode->next!=NULL){
            Lastnode=Lastnode->next;
        }
        Lastnode->next=temp;
    }
}

void swap(int * a,int * b){
    int temp=*a;
    *a=*b;
    *b=temp;
}

void pairwiseSwap(struct node * head){
    struct node * temp=head;
    while(temp!=NULL&&temp->next!=NULL){
        swap(&(temp->data),&(temp->next->data));
        temp=temp->next->next;
    }
}

void print(struct node * root){
    while(root!=NULL){
        printf("%d ",root->data);
        root=root->next;
    }
}


int main(){
    struct node * head=NULL;
    struct node * head1=NULL;
    //InsertAtBeg(&head,6);
    InsertAtBeg(&head,5);
    InsertAtBeg(&head,4);
    InsertAtBeg(&head,3);
    InsertAtBeg(&head,2);
    InsertAtBeg(&head,1);
    pairwiseSwap(head);
    print(head);
}