19.md

19 Remove Nth Node From End of List

Description

link

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Solution : TP

• uses p1 to move n steps
• uses p2 to catch p1 util p1 arrives the end of the list

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Code

Complexity T : O(N) M : O(1)

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def removeNthFromEnd(self, head, n):
        """
        :type head: ListNode
        :type n: int
        :rtype: ListNode
        """
        p1 = head
        p2 = head
        
        i = 0
        p1 = p1.next
        while p1.next != None:
            p1 = p1.next
            i = i + 1
            if i == n - 1:
                
        
        for i in range(n):
            p1 = p1.next
        
        p2 = head
        
        if not p1:
            return p2.next
        
        while p1.next != None:
            p1 = p1.next
            p2 = p2.next
        
        if p2.next.next:
            p2.next = p2.next.next
        else:
            p2.next = None
            
        return head