Euler totient function
Compute Euler's totient phi(n): the count of integers in [1, n] that are coprime to n, for n up to 10^12. Counting via per-element gcd is too slow; instead factorize n and apply the product formula phi(n) = n * product over distinct prime factors p of (1 - 1/p), implemented with integer arithmetic. Return 0 for n <= 0.
Implement
euler_totient(n: int) → intExamples
in
[12]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
[12]4not run yetsample