project euler problem 231

The prime factorisation of binomial coefficients

This problem is very simple. It is actually almost doing the same thing as problem 429 does. I checked my old code. It takes more than 3 seconds to get the answer since I did not manage those factors very well. I revised the code a little bit. Now it only takes less than 0.5 second.

project euler problem 203

Square-free Binomial Coefficients

This problem is too simple. The number of lines is too small, there are only limited numbers to be checked. I was using factorization in my old code, but I found that it was not necessary at all.

There are one or two more challenging PE problem closely related to this problem.