We hope that no difficulties, misunderstanding and "wtf am i asked to do" thoughts ruined your fun!
Problem A: Nash equilibrium Problem C: Segment tree or Fenwick? Problem E: Amazing bitset
In problems F, G and J we don't mention in the editorial that we assume you to have parsed the statement into a convenient programming-friendly format.
Problem F: Keep talking and nobody explodes -- easy Problem G: Keep talking and nobody explodes -- medium Problem H: Who needs suffix structures? Problem J: Keep talking and nobody explodes -- hard