Hiring process8 levels
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  2. 2 Additional Online Test (If Required)
  3. 3 Office Interview with Hiring Manager
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  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 > Count Evens in a Range > Editorial

Count Evens in a Range — Solution & Editorial

Back to the Problem

Precompute a prefix array of even-indicator counts; each query combines two prefix values (pre[R] − pre[L−1]).

Complexity: O(N + Q)