I decided to use paiza, which is frequently used personally because of the large number of problems in implementing Java programming problems. paiza has skill check problems, and since they are allowed to be disclosed to the outside, they carefully write “Please use them as teaching materials”. Also, since there are many languages other than Java, I think it would be useful if you want to study another language. ![Screenshot 2020-08-11 14.22.07.png](https://qiita-image-store.s3.ap-northeast-1.amazonaws.com/0/687827/7554faa2-59a7-8651-32b8-(558433edf84c.png)
Skill check problem
You can challenge up to B rank (S rank for problems without external disclosure).
Since there was a part where I couldn’t immediately understand how the problem was raised and the conditions, I would like to first try the sample problem to get a feel for it. There is no time limit for level-up problems, so it is easy to repeat where you have forgotten.