Hello Codeforces I have solved a lot of A,B,C problems. I am easily able to solve A,B,C problems but I am struggling a lot in D,E level problems. For example I am trying to solve problem D2 from Yesterday Div 3 round Codeforces Round #748 Div 3 D2. I was able to solve D1 in 5-7 min And i am struggling from D2 from last 4-5 hr. and basically I dont have idea how to solve it.
Is there are some special different type of methods used to solve harder problems
Also please mention Algorithms,Data structures,and methods needed to learn to solve harder (E,F) problems.
Thanks in advance :)