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65 lines
1.4 KiB
Plaintext
65 lines
1.4 KiB
Plaintext
---
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title: '19. Remove Nth Node From End of List'
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description: Given the head of a linked list, remove the n^th node from the end of the list and return its head
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icon: dot
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topics:
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- { name: "Linked List", slug: "linked-list" }
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- { name: "Two Pointers", slug: "two-pointers" }
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issue: "https://github.com/prdlk/leetcode/issues/80"
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sidebar:
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label: 'Remove Nth Node From End of List'
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badge: 'Medium'
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---
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::::warning
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Could you do this in one pass?
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::::
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### Example 1:
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- Input: `head = [1,2,3,4,5], n = 2`
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- Output: `[1,2,3,5]`
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### Example 2:
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- Input: `head = [1], n = 1`
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- Output: `[]`
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### Example 3:
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- Input: `head = [1,2], n = 1`
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- Output: `[1]`
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### Constraints:
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- The number of nodes in the list is sz.
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- `1 <= sz <= 30`
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- `0 <= Node.val <= 100`
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- `1 <= n <= sz`
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## Solution
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```py
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# Definition for singly-linked list.
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# class ListNode:
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# def __init__(self, val=0, next=None):
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# self.val = val
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# self.next = next
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class Solution:
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def removeNthFromEnd(self, head: ListNode | None, n: int) -> ListNode | None:
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dummy = ListNode(0)
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dummy.next = head
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fast = dummy
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for _ in range(n):
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if fast.next is None:
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return head
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fast = fast.next
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slow = dummy
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while fast.next is not None:
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slow = slow.next
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fast = fast.next
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slow.next = slow.next.next
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return dummy.next
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```
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