19. Remove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head.
For example,
Given linked list: 1->2->3->4->5, and n = 2.
After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:
Given n will always be valid. Try to do this in one pass.
Solution: Two Pointers
class Solution(object):
def removeNthFromEnd(self, head, n):
"""
:type head: ListNode
:type n: int
:rtype: ListNode
"""
slow = dummy = ListNode(None)
fast = dummy.next = head
for _ in xrange(n):
fast = fast.next
while fast:
slow = slow.next
fast = fast.next
if slow.next:
slow.next = slow.next.next
return dummy.next