Hiring process8 levels
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  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 > Flip and Slide > Editorial

Flip and Slide — Solution & Editorial

Back to the Problem

Coin-turning games decompose: the whole position's Grundy value is the XOR of single-heads-coin games. A heads at 0-indexed position i has Grundy value i, so XOR the indices (0-based) of all heads.

Complexity: O(N)