CodeForces Contest Problem Difficuilty Tags Edu Round 20 803A Maximal Binary Matrix M+ Greedy 803C Maximal GCD M+ Math Edu Round 63 1115C Alarm_Clocks_Everywhere M+ Math 1115D Beautiful-Array H- DP Round 555 Div3 1157C Increasing-Subsequence M+ 1157D N_Problems_During_K_Days M+ 1157F Maximum-Balanced-Circle H- Round 556 Div2 1150A Stock_Arbitraging M Greedy 1150D Three-Religions H DP Edu Round 64 1156C Ugly-Pairs H- greedy 1156C Match-Points H- greedy 1156D 0-1-Tree H union-find Round 557 Div2 1162C Hide-and-Seek M+ greedy 1162D Chladni-Figure H string, KMP Round 558 Div2 1163B Cat-Party M+ Hash 1163C Power-Transmission H- Hash 1163D Mysterious-Code H+ DP, KMP Round 559 Div2 1159C The-Party-and-Sweets H- greedy 1159D The-minimal-unique-substring H greedy, string Round 560 Div3 1165E Two-Arrays-and-Sum-of-Functions M+ greedy 1165F Microtransactions H greedy, binary search Edu_65 Div2 1167B Lost-Numbers M math, hash 1167D Bicolored-RBS M greedy, string 1167E Range-Deleting H+ greedy Round_561 Div2 1166B All-the-Vowels-Please M math 1166C A-Tale-of-Two-Lands H math, two pointers 1166D Cute-Sequences H math, binary search 1166E The-LCMs-Must-be-Large H math, bit Global Round 3 1148B Born-This-Way H- greedy 1148C Crazy-Diamond H- greedy 1148D Dirty-Deeds-Done-Dirt-Cheap H- greedy Edu_66 Div2 1175C Electrification M+ two pointers 1175D Array-Splitting H- math 1175E Minimal-Segment-Cover H greedy, binary search Round_564_Div2 1173C Nauuo-and-Cards H greedy 1173D Nauuo-and-Circle H geometry, combinations Round_562_Div2 1169B Pairs H- recursion 1169C Increasing-by-Modulo H- greedy, binary search 1169D Good-Triple H string, greedy 1169E And-Reachability H DP Edu_67 Div2 1187D Subarray-Sorting H+ greedy, BIT 1187E Tree-Painting H graph, tree Round_581_Div2 1204C Anna-Svyatoslav-and-Maps H- graph 1204D Kirk-and-a-Binary-String H greedy, string Edu_Round_72 1217B Zmei-Gorynich M math 1217C The-Number-Of-Good-Substrings M+ greedy 1217D Coloring-Edges H dfs, graph Edu_Round_73 1221D Make-The-Fence-Great-Again H- dp Round_587_Div3 1216C White-Sheet M+ math Forethought 1146C Tree-Diameter H- graph, recursive Edu_Round_78 1278C Berry-Jam M Hash 1278D Segment-Tree M+ greedy, Heap Round_78_Div2 1282B K-for-the-Price-of-One H- greedy 1282C Petya-and-Exam H- greedy Edu_Round_79 1279D Santa's-Bot M+ math, probability Goodbye-2019 1270C Make-Good H- math 1270D Strange-Device M+ math Round_611_Div3 1283C Friends-and-Gifts M math 1283D Christmas-Trees M+ BFS 1283E New-Year-Parties M+ greedy Edu_Round_80 1288C Two-Arrays H- math, dp 1288D Minimax-Problem H- binary search, bit Edu_Round_82 1303D Fill-The-Bag M+ math,bit Round_627 Div3 1324E Sleeping-Schedule M+ dp 1324F Maximum-White-Subtree H- dfs,graph Round_622 Div2 1313C Skyscrapers H- stack,dp Round_626 Div2 1323B Count-Subrectangles M+ math Edu_Round_85 1334C Circle-of-Monsters M+ math,greedy Round_617_Div3 1296D Fight-with-Monsters M+ math,greedy 1296E1 String-Coloring M+ greedy VK_Cup 1310A Recommendations H- greedy,multiset Round_675_Div2 1422D Returning-Home H Dijkstra