MediumLinked Lists
Remove Nth Node From End of List
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Given the head of a linked list, remove the nth node from the end of the list and return its head.
Example 1:
Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]
Explanation: After removing the 2nd node from the end, the list becomes [1,2,3,5].
Example 2:
Input: head = [1], n = 1
Output: []
Explanation: The only node is removed, resulting in an empty list.
Example 3:
Input: head = [1,2], n = 1
Output: [1]
Explanation: After removing the last node, the list becomes [1].
Examples
Example 1
Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]
Explanation: The 2nd node from the end is 4. After removing it, the linked list becomes 1 -> 2 -> 3 -> 5.
Example 2
Input: head = [1], n = 1
Output: []
Explanation: There is only one node in the list and it is removed, resulting in an empty list.
Example 3
Input: head = [1,2], n = 1
Output: [1]
Explanation: The 1st node from the end is 2. After removing it, the linked list becomes just [1].
Constraints
- -The number of nodes in the list is sz.
- -1 <= sz <= 30
- -0 <= Node.val <= 100
- -1 <= n <= sz
Optimal Complexity
Time
O(n)
Space
O(1)
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