1669. Merge In Between Linked Lists.py

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def mergeInBetween(self, list1: ListNode, a: int, b: int, list2: ListNode) -> ListNode:
        prev = list1
        temp1 = list1
        curr = list1
        a -= 1  
        
        while temp1 and a > 0:
            temp1 = temp1.next
            prev = temp1
            a -= 1
        
        temp1 = list1  
        

        while temp1 and b > 0:
            temp1 = temp1.next
            curr = temp1
            b -= 1
        
        temp2 = list2  
        
        while temp2.next:
            temp2 = temp2.next
        
        prev.next = list2  
        temp2.next = curr.next 
        
        return list1