Hiring process8 levels
  1. 1 IQ Test
  2. 2 Additional Online Test (If Required)
  3. 3 Office Interview with Hiring Manager
  4. 4 Unpaid Test Task (Motivation Check)
  5. 5 Paid Test Task and Follow-Up Interview
  6. 6 Iterative Paid Test Tasks
  7. 7 Office Verification
  8. 8 Final Interview with the Founder

Problems > Climbing Stairs (1,2,3) > Editorial

Climbing Stairs (1,2,3) — Solution & Editorial

Back to the Problem

The count is the tribonacci recurrence f(n)=f(n−1)+f(n−2)+f(n−3); use 3×3 matrix exponentiation for huge N.

Complexity: O(log N)