Digit sum divisible by k
Count how many integers in the inclusive range [L, R] have a digit sum divisible by k. L and R can be large (up to about 10^15), so iterate over digits, not values. Assume 0 <= L <= R and k >= 1. Note 0 counts if it falls in range and 0 is divisible by k.
Implement
count_digitsum_divisible(L: int, R: int, k: int) → intExamples
in
[1,20,3]out6What 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 30 min
solution.py
InputExpectedGot
[1,20,3]6not run yetsample