「USACO 2021 US Open Platinum」Balanced Subsets
「USACO 2021 US Open Platinum」United Cows of Farmer John
CF715E - Complete the Permutations
CF1503E - 2-Coloring
CF1392H - ZS Shuffles Cards
多项式与点值式
CF1499G - Graph Coloring
CF1288F - Red-Blue Graph
CF1491G - Switch and Flip
CF1264E - Beautiful League