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 > All Digits Different > Editorial

All Digits Different — Solution & Editorial

Back to the Problem

Digit walk with a used-set: for each prefix position try smaller digits not yet used and multiply falling-factorial choices for the free tail; add 1 if N itself survives. (Beyond 10 digits nothing new qualifies.)

Complexity: O(10 · log N)