Count primes below n
Return the number of prime numbers strictly less than a given non-negative integer n. For example, there are 4 primes below 10 (2, 3, 5, 7). n can be up to 5,000,000. Aim for a solution that runs well within a few seconds at the upper bound.
Implement
count_primes(n: int) → intExamples
in
[10]out4What a strong answer looks like
State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.
0:00 of about 18 min
solution.py
InputExpectedGot
[10]4not run yetsample