Day 1~10
day01 104 Warehouse location (absolute value inequality)
day02 898 digital triangle (dynamic programming)
day03 756 serpentine matrix (offset technique)
day04 1113 Red and black (flood fill algorithm, namely DFS, BFS)
day05 1346 palindrome square (carry system, double pointer)
day06 680 Cut the rope (floating point two points)
day07 1227 points chocolate (two integers)
day08 422 The tree outside the school gate (interval merge)
day09 429 scholarship (multi-keyword sorting)
day10 1208 Flip the coin (recursive)
11th~20th day
day11 1532 Find coins (hash table, double pointer)
day12 1341 Friday the 13th (watching, simulation)
day13 754 square matrix II (find the law)
day14 1432 Board Challenge (DFS)
day15 1371 Currency system (complete knapsack problem)
day16 1381 factorial (control range)
day17 1353 ski resort design (enumeration)
day18 1603 integer set division (greedy)
day19 482 Chorus formation (linear DP)
21st~30th day
day21 1015 Picking peanuts (linear DP)
day22 55 Maximum sum of consecutive sub-arrays (linear DP)
day23 126 maximum sum (two-dimensional prefix sum)
day24 426 Happy Jin Ming (01 backpack problem)
day25 703 Sudoku check (simulation)
day26 1101 Bouquet for Algernon (BFS)
day28 433 ISBN number (analog)
day29 428 sequence (binary, mapping)
day30 421 Taotao apple picking (simple simulation)
31st~40th day
day31 417 Unhappy Jinjin (simple simulation)
day32 496 machine translation (simulation, queue)
day33 425 Obviously random number (sort, de-duplication)
day34 458 scale simplification (enumeration)
day35 441 digital statistics (enumeration)
day36 449 Prime factor decomposition (number theory, enumeration)
day37 445 digital reversal (string processing, simulation)
day38 1477 is spelled correctly (string processing, typing, simulation)
day39 3208 zigzag scan (diagonal of matrix, find regularity)
day40 3203 drawing (array notation)
End of days 41~43
day41 3232 Maximum fluctuation (enumeration)