1669 Merge In Between Linked Lists.java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode() {}
 *     ListNode(int val) { this.val = val; }
 *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
 * }
 */
class Solution {
    public ListNode mergeInBetween(ListNode list1, int a, int b, ListNode list2) {
        
        
        ListNode temp1=list1;
        
        for(int i=0;i<a-1;i++) {
            temp1=temp1.next;
        }
        ListNode temp2=temp1;
        for(int i=a;i<=b;i++) {
            temp2=temp2.next;
        }
        temp1.next=list2;
        while(list2.next != null) {
            list2=list2.next;
            
        }
        list2.next=temp2.next;
        
        return list1;
        
    }
}