Count primes
Given an integer n (0 <= n <= 5e6), return the count of prime numbers strictly less than n. For example for n=10 the primes below it are 2,3,5,7 so the answer is 4. A sieve of Eratosthenes running in O(n log log n) is expected; trial-dividing each number is too slow 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 20 min
solution.py
InputExpectedGot
[10]4not run yetsample