Remaining of 2021.md

step 1: document what is available

• Collections

  • Counter: easily count duplicates and stuffs
  • DefaultMap: map that can create default values
    • TODO: assess if this is needed??
  • UnionFind: impl of union find

  • list

    • BracketStack: stack with annihilation rules
      • note: annihilation doesn't run when removing stuff

• graph

Old unfinished tasks