Equilateral Triangles
[USACO 2020 February Platinum]Help Yourself
2016 多校5 ATM
[HDU-6848] Expectation (2020多校7T5) (Dp)
[HDU-6854] Kcats (2020多校7 T11) (笛卡尔树+区间Dp)
[HDU - 6833] a Very Easy Math Problem (莫比乌斯反演)
回文自动机 (PAM,Palindrome Automaton)
[BoundedOptimization TopCoder - 12294]
[SweetFruits TopCoder - 12141](Matrix-Tree)