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 > Avoid the Set {00, 11, 22} > Editorial

Avoid the Set {00, 11, 22} — Solution & Editorial

Back to the Problem

Build an Aho–Corasick automaton over the forbidden set, propagate terminal flags along fail links, drop dead states, and raise the surviving transfer matrix to the N-th power.

Complexity: O(S3 log N)

Watch out: A state is dead if it or any fail-ancestor completes a pattern; those must be excluded from the matrix.