Project Euler #156: Counting Digits

  • + 2 comments

    As my code times out, I wonder how can we be sure that the sum s(d) is finite?

    For example, if I test the case b=10 and d=1, I get:

    f(n,1)=n for n=0

    f(n,1)=n for n=1

    f(n,1)=n for n=199981

    f(n,1)=n for n=199982

    f(n,1)=n for n=199983

    f(n,1)=n for n=199984

    f(n,1)=n for n=199985

    f(n,1)=n for n=199986

    f(n,1)=n for n=199987

    f(n,1)=n for n=199988

    f(n,1)=n for n=199989

    f(n,1)=n for n=199990

    f(n,1)=n for n=200000

    f(n,1)=n for n=200001

    f(n,1)=n for n=1599981

    ...

    f(n,1)=n for n=35199990

    f(n,1)=n for n=35200000

    f(n,1)=n for n=35200001

    ....