問題の意図を読み間違えて無駄に苦戦。 https://www.hackerrank.com/contests/101hack47/challenges/summing-in-a-tree

Cよりラクでした。 https://www.hackerrank.com/contests/101hack47/challenges/watson-and-dag

せっかくDE解けたのにCが間に合わず。 https://www.hackerrank.com/contests/101hack47/challenges/basketball-game