61. Rotate List

#linear searching so tc is O(n) andd there is no extra memory is used so sc is O(1)
# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def rotateRight(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:
        if not head:
            return None
        len=1
        tail=head
        while(tail.next):
            tail=tail.next
            len+=1
        #if the no of rotation is same as the length is being end up with the same list
        p=k%len
        print(p)
        if(p==0):
            return head
        cur=head
        #finding the postion to break the list
        p=len-p-1
        while(p):
            cur=cur.next
            p-=1
        
        newhead=cur.next
        cur.next=None
        tail.next=head
        return newhead