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  2. 2 Additional Online Test (If Required)
  3. 3 Office Interview with Hiring Manager
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Problems > The K-th Triangular Number > Editorial

The K-th Triangular Number — Solution & Editorial

Back to the Problem

Apply the sequence's closed form (or index a precomputed list for Fibonacci / powers).

Complexity: O(1)

Watch out: The result approaches 1018 — 64-bit arithmetic.