swappin_nodes_in_linked_list

Name - Swapping Nodes In the Linked List 
Dificulty - Medium 
Problem number - 1712 
Link : https :  leetcode.com/problems/swapping-nodes-in-a-linked-list/

#include <bits/stdc++.h>
 using namespace std;
#define ll long long
#define s string

/*------------------------------------------*/
/*    Author : Sahil Shile                  */
/*    Walchand College of Engineering, Sangli*/
/*--------------------------------------------*/

struct ListNode {
    int val;
    ListNode *next;
    ListNode() : val(0), next(nullptr) {}
    ListNode(int x) : val(x), next(nullptr) {}
    ListNode(int x, ListNode *next) : val(x), next(next) {}
};

int getLength(ListNode *head)
{
    ListNode *temp = head;
    int cnt = 0;
    while (temp != NULL)
    {
        cnt++;
        temp = temp->next;
    }
    return cnt;
}
    ListNode *swapNodes(ListNode *head, int k)
    {
        int length = getLength(head);
        int a = 1, b = 1;
        ListNode *end = head;
        ListNode *start = head;
        while (a < k)
        {
            end = end->next;
            a++;
        }
        while (b < length - k + 1)
        {
            start = start->next;
            b++;
        }
        int temp = start->val;
        start->val = end->val;
        end->val = temp;
        return head;
    }


void insertAtHead(ListNode *&head, int x)
{
    ListNode *temp = head;
    ListNode *newNode = new ListNode(x);
    if (head != NULL)
    {
        newNode->next = head;
        head = temp;
    }
    else
    {
        head = newNode;
    }
}

int main(){
ListNode* node1=new ListNode(10);
ListNode* head=node1;
insertAtHead(head,11);
insertAtHead(head,12);
insertAtHead(head,13);
int n;
cin>>n;
ListNode* ans= swapNodes(head,n);
return 0;
}