I have found that for me, a classical musicians although somewhat mathematically inclined, most problems up to about problem 100 were solvable with my maths book and some helpful pointers.
I ended up spending too much time per problem (days to weeks) and then I got a kid, so that time is being spent on better things.
My advanced algorithms professor at University has the prerequisite for doing research with him of solving Project Euler questions from 1-100. He had some sort of time table on it like 1-3 months, but also said if you solved them all in a shorter period like 1 week that you were too good to learn anything from doing research with him.
So, honestly you just doing 1-100 as a classical musician is really surprising and amazing to me. Great job!
What exactly do you want a link to? I just used my friend's old maths books from high school (he did all 7 courses available, which means about 25% of his 3 year HS studies. It includes stuff like linear algebra and linear optimization and game theory. ) and lots of time.
He went on to become a PhD in maths and just pointed me in the right direction when I couldn't figure stuff out myself.
I ended up spending too much time per problem (days to weeks) and then I got a kid, so that time is being spent on better things.