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Linked List•Pattern: Two Pointers•Medium

Remove the Nth node from the end of a linked list

Problem Intuition & Objective

Delete the Nth node from the end in one pass.

Time ComplexityO(n)
Optimal
Space ComplexityO(1)
Memory Bounds
Optimal Algorithmic Approach

Two-pointer with N-step lead: one pass, O(n).

Core Invariants & Edge Cases

  • Use two pointers: advance the first pointer N+1 steps ahead
  • Then advance both until first reaches null
  • Second pointer is now at the node before the target; update next pointer
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