Program to make middle node head in Linked List - codeitwise

Here we are going to write a program to make middle node head in linked list. Suppose we are having n number of nodes in the linked list, if n is odd then n/2 is the middle node so in that case we will change the head and make the (n/2)th node head and if n is even then n/2 + 1 will be the middle node so in that case we will set the (n/2 + 1)th node head.

Suppose,

Input- 1 => 2 => 3 => 4 => 5 => NULL

Output- 3 => 1 => 2 => 4 => 5 => NULL

So now lets implement it 

Program to make middle node head in Linked List-

 C Code-

#include <stdio.h>
#include <malloc.h>

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

void create(struct node** head,int val){
    struct node* temp=*head;
    struct node* newnode=(struct node*)malloc(sizeof(struct node));
    newnode->data=val;
    newnode->next=NULL;
    if(*head==NULL){
        *head=newnode;
        return;
    }
    while(temp->next!=NULL){
        temp=temp->next;
    }
    temp->next=newnode;
}
int length(struct node* head){
    struct node* temp=head;
    int c=0;
    while(temp->next!=NULL){
        temp=temp->next;
        c=c+1;
    }
    return c/2;
}
void makemiddlehead(struct node** head,int pos){
    struct node* temp=*head;
    struct node* t;
    int c=1;
    while(c!=pos){
        temp=temp->next;
        c=c+1;
    }
    t=temp->next;
    temp->next=temp->next->next;
    t->next=*head;
    *head=t;
    // return head;
}
void display(struct node* head){
    while(head!=NULL){
        printf("%d => ",head->data);
        head=head->next;
    }
    printf("NULL\n");
}
int main(){
    struct node* head=NULL;
    create(&head,1);
    create(&head,2);
    create(&head,3);
    create(&head,4);
    create(&head,5);
    create(&head,6);
    create(&head,7);
    display(head);
    int l=length(head);
    makemiddlehead(&head,l);
    display(head);
    return 0;
}

Output-

1 => 2 => 3 => 4 => 5 => 6 => 7 => NULL
4 => 1 => 2 => 3 => 5 => 6 => 7 => NULL

Time Complexity: O(n) where n is the length of the linked list.

Linked List Problems- 

• Count Number of Occurrence of given integer in Linked List

• Find Length of Loop in Linked List

• Delete Duplicate Elements from Sorted Linked List

• Position Even and Odd Nodes Together