这些年打过的比赛codeforces

这些年打过的比赛codeforces

Codeforces Round #654 (Div. 2)   参与排名人数14349   本场比赛主要心思放在观摩高手如何打比赛，发现初中生真的很厉害。

[codeforces 1374B] Magical Calendar 看懂题意是关键+画图找规律

Codeforces Round #653 (Div. 3)   参与排名人数11687

[codeforces 1374A] Required Remainder 带余除法(该词来自初等数论)

[codeforces 1374B] Multiply by 2, divide by 6 统计3的幂次+统计2的幂次

[codeforces 1374C] Move Brackets 括号()配对

[codeforces 1374D] Zero Remainder Array 跳跃补缺

[codeforces 1374E1] Reading Books (easy version) 巧妙配对

[codeforces 1374F] Cyclic Shifts Sorting 按规则先排最小再排最大

Educational Codeforces Round 90 (Rated for Div. 2)   参与排名人数12840

[codeforces 1373A] Donut Shops 选一个还是选一堆

[codeforces 1373B] 01 Game 删除01或10的博弈

[codeforces 1373C] Pluses and Minuses 找规律,难在+号会使数据发生跳跃,跳过了中间的+号

[codeforces 1373D] Maximum Sum on Even Positions 翻转不改变相对位置+两种交换形式

[codeforces 1373E] Sum of Digits 十位数百位数乃至更高位的进位不可能发生

Codeforces Round #652 (Div. 2)   参与排名人数14647

[codeforces 1369A] FashionabLee 正多边形

[codeforces 1369B] AccurateLee 寻找左边界的1,右边界的0

[codeforces 1369C] RationalLee 自大到小分配+自少向多分配+不定长数组的使用

[codeforces 1369D] TediousLee 树上找规律

Codeforces Round #651 (Div. 2)  参与排名人数14559

[codeforces 1370A] Maximum GCD 找n/2的值

[codeforces 1370B] GCD Compression 构造共有因子为2的数组集合

[codeforces 1370C] Number Game 质因数分解+坑点贼多

[codeforces 1370D] Odd-Even Subsequence 二分查找+跳跃取数

[codeforces 1370E] Binary Subsequence Rotation 两种旋转形式

Codeforces Global Round 8  参与排名人数13404

[codeforces 1368A] C+= 斐波那契数列+数据范围有误

[codeforces 1368B] Codeforces Subsequences 乘法原理

[codeforces 1368C] Even Picture 阶梯式的构造

[codeforces 1368D] AND, OR and square sum 操作过后各个位上1的数量竟然不变

Codeforces Round #650 (Div. 3)  参与排名人数11978

[codeforces 1367A] Short Substrings 间隔取字符

[codeforces 1367B] Even Array 统计余数情况

[codeforces 1367C] Social Distance 判定连续的k个数是0

[codeforces 1367D] Task On The Board 设置位置的优先级

[codeforces 1367E] Necklace Assembly 根据周期进行分块,每块相应位置的字母都需雷同

Codeforces Round #649 (Div. 2)  参与排名人数11286

[codeforces 1364A] XXXXX 余数的拆分

[codeforces 1364B] Most socially-distanced subsequence 绝对值脱壳的4种形态

[codeforces 1364C] Ehab and Prefix MEXs MEX数据生成

Educational Codeforces Round 89 (Rated for Div. 2)  参与排名人数13281

[codeforces 1366A] Shovels and Swords 公式推导+取值限制

[codeforces 1366B] Shuffle 区间交叠+区间合并

[codeforces 1366C] Palindromic Paths 将值需相同的位置找出，统计其中0,1个数

[codeforces 1366D] Two Divisors 互质公式推导+线性筛素数

[codeforces 1366E] Two Arrays 双指针+乘法原理+注意边界处理

Codeforces Round #648 (Div. 2)  参与排名人数13231

[codeforces 1365A] Matrix Game 管住行守住列

[codeforces 1365B] Trouble Sort 只要存在b[i]!=b[j],就一定能换成最后的非递减序列

[codeforces 1365C] Rotation Matching 寻找偏移量

[codeforces 1365D] Solve The Maze 遍历矩阵的深搜dfs+隔断的设置

[codeforces 1365E] Maximum Subsequence Value 或运算+为什么选三个元素对应最大值

[codeforces 1365F] Swaps Again 以不变应万变

Codeforces Round #647 (Div. 2) - Thanks, Algo Muse!  参与排名人数12044

[codeforces 1362A] Johnny and Ancient Computer 倍数关系用2的幂次统计

[codeforces 1362B] Johnny and His Hobbies 异或+排序

[codeforces 1362C] Johnny and Another Rating Drop 打表+按位找规律

[codeforces 1362D] Johnny and Contribution 验证拓扑排序

[codeforces 1362E] Johnny and Grandmaster p进制

Codeforces Round #646 (Div. 2)  参与排名人数14203

[codeforces 1363A] Odd Selection 偶数不够奇数来补

[codeforces 1363B] Subsequence Hate 最终有4种形态+前缀和

[codeforces 1363C] Game On Leaves 树上分胜负

[codeforces 1363D] Guess The Maximums 交互式程序+二分查找

[codeforces 1363E] Tree Shuffling 可以回避排序的树上结构(链式结构不超时的写法)

Educational Codeforces Round 88 (Rated for Div. 2)  参赛人数19992

[codeforces 1359A] Berland Poker 抽屉原理

[codeforces 1359B] New Theatre Square 2块对应的数量统计

[codeforces 1359C] Mixing Water 公式推导+浮点数化整数+绝对值脱壳的4种形态

[codeforces 1359D] Yet Another Yet Another Task 当前元素为峰值进行蚕食

[codeforces 1359E] Modular Stability 快速幂+乘法逆元+组合数计算+找规律

Codeforces Round #645 (Div. 2)  参与排名人数14819

[codeforces 1358A] Park Lighting 向上取整

[codeforces 1358B] Maria Breaks the Self-isolation 叫上所有伙伴 (自小到大排序+逆序处理)

[codeforces 1358C] Celex Update 找规律+猜公式

[codeforces 1358D] The Best Vacation 有个数限制的最大连续子段和

Codeforces Round #644 (Div. 3)  参赛人数20688

[codeforces 1360A] Minimal Square 关键词identical

[codeforces 1360B] Honest Coach 排序+找相邻差值最小的两个数

[codeforces 1360C] Similar Pairs 坑点较多

[codeforces 1360D] Buying Shovels 在指定范围内找最大约数

[codeforces 1360E] Polygon 自底向上,自右向左分析

[codeforces 1360F] Spy-string 难想的爆搜

[codeforces 1360G] A/B Matrix 横竖都一样+紧凑排列

Educational Codeforces Round 87 (Rated for Div. 2)  参与排名人数11499,比赛前遇到2次延时,17:05-17:15,17:15-17:20

[codeforces 1354A] Alarm Clock 难在题意的解读

[codeforces 1354B] Ternary String 寻找6种组合

[codeforces 1354C1] Simple Polygon Embedding 找外接圆

[codeforces 1354C2] Not So Simple Polygon Embedding 几何画板

[codeforces 1354D] Multiset 线段树(由数值找节点位置,由排名找节点位置)

Codeforces Round #643 (Div. 2)  参与排名人数11475

[codeforces 1355A] Sequence with Digits 十进制转换+打表找规律

[codeforces 1355B] Young Explorers 题意难懂

[codeforces 1355C] Count Triangles 公式推导+找规律+双指针+排列组合中的乘法原理

[codeforces 1355D] Game With Array 极端的构造

Codeforces Round #642 (Div. 3)  参与排名人数11823

[codeforces 1353A] Most Unstable Array 照着葫芦画瓢

[codeforces 1353B] Two Arrays And Swaps 若数组a中最小值小于b中最大值，将其用b中最大值替换

[codeforces 1353C] Board Moves 画图找规律

[codeforces 1353D] Constructing the Array 分治算法

[codeforces 1353E] K-periodic Garland 为什么会想到动归dp

Codeforces Round #641 (Div. 2)   参与排名人数11937

[codeforces 1350A] Orac and Factors 找规律

[codeforces 1350B] Orac and Models 约数+深搜dfs

[codeforces 1350C] Orac and LCM 最大公约数+最小公倍数+公式推导

[codeforces 1350D] Orac and Medians 在连续串(串长为2或3)中找2个大于等于k的元素

Codeforces Round #640 (Div. 4)   参与排名人数9749,终于弄明白账号前*的意义,*out of competition,也即虽然该用户参加本场比赛,但不参与排名。

[codeforces 1352A] Sum of Round Numbers 十进制转换

[codeforces 1352B] Same Parity Summands 奇数偶数二选一

[codeforces 1352C] K-th Not Divisible by n 周期

[codeforces 1352D] Alice, Bob and Candies 每人两个指针+前缀和

[codeforces 1352E] Special Elements 桶排序+前缀和

[codeforces 1352F] Binary String Reconstruction 先处理00,再处理11,最后处理(01或10)

[codeforces 1352G] Special Permutation 构造偶数序列,奇数序列,合并

Testing Round #16 (Unrated)   测试人数4695

[codeforces 1351A] A+B (Trial Problem) 加法运算

[codeforces 1351B] Square? 拼接成正方形

[codeforces 1351C] Skier 区分出不同位置+连成图+找重边/map+pair的写法/set+pair的写法

Codeforces Round #639 (Div. 2)   5月3日,正要开打前5分钟,来了句Codeforces Round #639: the round is rescheduled,5月6日开打，遇到了测试要排长长的队伍(印象中IOI比赛是这样),抓狂,唯一慰藉的是,此场Unrated。   比赛人数13765

[codeforces 1345A] Puzzle Pieces 注意one blank

[codeforces 1345B] Card Constructions 找规律

[codeforces 1345C] Hilbert's Hotel 找规律+周期+转圈圈(模)

Codeforces Round #638 (Div. 2)  比赛人数15215

[codeforces 1348A] Phoenix and Balance 一个顶俩

[codeforces 1348B] Phoenix and Beauty 找周期

[codeforces 1348C] Phoenix and Distribution 5种形态

[codeforces 1348D] Phoenix and Science 从两个极端结果出发,找到中间结果

Educational Codeforces Round 86 (Rated for Div. 2)  比赛人数15356

[codeforces 1342A] Road To Zero 两种选择有优劣

[codeforces 1342B] Binary Period 周期要么是1要么是2

[codeforces 1342C] Yet Another Counting Problem 犬牙交错

[codeforces 1342D] Multiple Testcases 均匀安置

[codeforces 1342E] Placing Rooks 容斥原理

Codeforces Round #637 (Div. 2) - Thanks, Ivan Belonogov!   比赛人数15390

[codeforces 1341A] Nastya and Rice 区间交叠

[codeforces 1341B] Nastya and Door 神奇的掐头去尾+前缀和

[codeforces 1341C] Nastya and Strange Generator 让人郁闷的题

[codeforces 1341D] Nastya and Scoreboard 二进制运算+布尔背包

Codeforces Round #636 (Div. 3)   比赛人数12253

[codeforces 1343A] Candies 等比数列求和公式

[codeforces 1343B] Balanced Array 奇+奇=偶,奇+偶=奇,偶+偶=偶

[codeforces 1343C] Alternating Subsequence 在连续负数或正数区间内找最大值

[codeforces 1343D] Constant Palindrome Sum 寻找需改变区间的边界+前缀和

[codeforces 1343E] Weights Distributing SPFA+中转的路径

[codeforces 1343F] Restore the Permutation by Sorted Segments 从假定出发的尝试

Codeforces Round #635 (Div. 2)   比赛人数14830

[codeforces 1337A] Ichihime and Triangle 两边之和大于第三边

[codeforces 1337B] Kana and Dragon Quest game 公式推导

[codeforces 1337C] Linova and Kingdom 公式推导

[codeforces 1337D] Xenia and Colorful Gems 寻找6种组合

[codeforces 1337E] Kaavi and Magic Spell 区间动归dp

[codeforces 1337F] Yui and Mahjong Set 公式推导+交互式程序的测试

Codeforces Round #634 (Div. 3)   比赛人数11922  慢慢的对Div. 3难度有了些感觉

[codeforces 1335A] Candies and Two Sisters 注意n是奇偶的情况

[codeforces 1335B] Construct the String b代表周期

[codeforces 1335C] Two Teams Composing 统计技能种类数量+统计同一技能最大数量

[codeforces 1335D] Anti-Sudoku 寻找需要更新的位置

[codeforces 1335E1] Three Blocks Palindrome (easy version) 分成左中右3个区间+前缀和

[codeforces 1335E2] Three Blocks Palindrome (hard version) 从中间位置向两边扩散

[codeforces 1335F] Robots on a Grid 倍增

Codeforces Round #633 (Div. 2)   比赛人数12032  打完atcoder还没歇脚，紧接着就是codeforces

[codeforces 1339A] Filling Diamonds 给我一张有图的纸

[codeforces 1339B] Sorted Adjacent Differences 排序后将数据分组,合并

[codeforces 1339C] Powered Addition 填上最大的坑

Educational Codeforces Round 85 (Rated for Div. 2)   比赛人数14824

[codeforces 1334A] Level Statistics 坑点较多

[codeforces 1334B] Middle Class 多退少补

[codeforces 1334C] Circle of Monsters 公式推导+变环形关系为直线关系+前缀和

[codeforces 1334D] Minimum Euler Cycle 找规律

Codeforces Round #632 (Div. 2)   比赛人数12810

[codeforces 1333A] Little Artem 读懂题+找规律+多举例

[codeforces 1333B] Kind Anton 统计区间0,1,-1出现的情况

[codeforces 1333C] Eugene and an array 寻找位置i所辖的最远位置

[codeforces 1333D] Challenges in school №41 在整体移动中,记录个体移动的信息

[codeforces 1333E] Road to 1600 构造+蛇形

[codeforces 1333F] Kate and imperfection 先加入所有质数,再加入最大约数为２的数,紧接着加入最大约数为３的数,以此类推

Codeforces Round #631 (Div. 1) - Thanks, Denis aramis Shitov!   比赛人数1273

 

Codeforces Round #631 (Div. 2) - Thanks, Denis aramis Shitov!   比赛人数10889

[codeforces 1330A] Dreamoon and Ranking Collection 连续递增序列判定

[codeforces 1330B] Dreamoon Likes Permutations 合理分块

[codeforces 1330C] Dreamoon Likes Coloring 极端处理,再图变通

[codeforces 1330D] Dreamoon Likes Sequences 数据分组+乘法原理

[codeforces 1330E] Drazil Likes Heap 堆元素删除+堆深度+贪心

April Fools Day Contest 2020   真的是愚人节的题目，好吧，不打了，睡觉去了

Codeforces Round #630 (Div. 2)   比赛人数12012

[codeforces 1332A] Exercising Walk 排除所有不可能，剩下的就是可能

[codeforces 1332B] Composite Coloring 不超过11种颜色的证明

[codeforces 1332C] K-Complete Word 切割成k长子串,在子串中,根据中心对称,保留数量最多的字母

[codeforces 1332D] Walk on Matrix 构造

[codeforces 1332E] Height All the Same 奇偶构造+排列组合+快速幂+二项式定理+乘法逆元

Codeforces Round #629 (Div. 3)   比赛人数10967

[codeforces 1328A] Divisibility Problem 整除+模

[codeforces 1328B] K-th Beautiful String 研究倒数第二个字母b的位置

[codeforces 1328C] Ternary XOR 题意易懂,但不好编

[codeforces 1328D] Carousel 分类讨论

Educational Codeforces Round 84 (Rated for Div. 2)   比赛人数13522

[codeforces 1327A] Sum of Odd Integers 公式推导+奇偶判定

[codeforces 1327B] Princesses and Princes 过长的题目+难懂的题意

[codeforces 1327C] Game with Chips 有点象飞行棋

[codeforces 1327E] Count The Blocks 打表找规律+根据规律找公式+优化公式

Codeforces Global Round 7   比赛人数10630

[codeforces 1326A] Bad Ugly Numbers 构造由2,3,4组成的不能被3整除的奇数

[codeforces 1326B] Maximums 公式推导

[codeforces 1326C] Permutation Partitions 排列组合

[codeforces 1326D1] Prefix-Suffix Palindrome (Easy version) 首尾回文+自左往右最大回文+自右往左最大回文

[codeforces 1326D2] Prefix-Suffix Palindrome (Hard version) Manacher算法 马拉车算法

Codeforces Round #628 (Div. 2)   比赛人数9400

[codeforces 1325A] EhAb AnD gCd 公式推导

[codeforces 1325B] CopyCopyCopyCopyCopy 自小到大排序+unique去重成功应用

[codeforces 1325C] Ehab and Path-etic MEXs 绕不开的叶节点+特判

[codeforces 1325D] Ehab the Xorcist 异或+难点是最小个数

Codeforces Round #627 (Div. 3)   比赛人数6434

[codeforces 1324A] Yet Another Tetris Problem 熟悉而又陌生

[codeforces 1324B] Yet Another Palindrome Problem 回文+边界处理

[codeforces 1324C] Frog Jumps 一直向右+边界处理

[codeforces 1324D] Pair of Topics 分而治之+排列组合

Educational Codeforces Round 83 (Rated for Div. 2)   比赛人数8705

[codeforces 1312A] Two Regular Polygons 整除

[codeforces 1312B] Bogosort 逆序证明

[codeforces 1312C] Adding Powers 进制转换

[codeforces 1312D] Count the Arrays 排列组合+快速幂+乘法逆元+二项式定理

Codeforces Round #626 (Div. 2, based on Moscow Open Olympiad in Informatics)   比赛人数5260

[codeforces 1323A] Even Subset Sum Problem 奇+奇=偶,奇+偶=奇,偶+偶=偶

[codeforces 1323B] Count Subrectangles 分而治之+细节较多

[codeforces 1323C] Unusual Competitions 栈呼之欲出

CodeCraft-20 (Div. 2)   比赛人数7369

[codeforces 1316A] Grade Allocation 热身

[codeforces 1316B] String Modification 力挽狂澜

[codeforces 1316C] Primitive Primes 绝杀

Ozon Tech Challenge 2020 (Div.1 + Div.2, Rated, T-shirts + prizes!)   比赛人数7420

[codeforces 1305A] Kuroni and the Gifts 故弄玄虚

[codeforces 1305B] Kuroni and Simple Strings 有点象快排

[codeforces 1305C] Kuroni and Impossible Calculation 数据范围是突破

Codeforces Round #625 (Div. 2, based on Technocup 2020 Final Round)   比赛人数5638

[codeforces 1321A] Contest for Robots 题目有些长

[codeforces 1321B] Journey Planning hack来得太突然

[codeforces 1321C] Remove Adjacent 从字典序最大的字母开始处理

[codeforces 1321D] Navigation System 逆向最短路+题意解读

Kotlin Heroes: Episode 3   比赛人数912

快速做完第一题，迅速提交，编译错误，好吧，再提交一遍，说是提交雷同代码，无法提交，定睛一看，编译语言是Kotlin

上下寻找，发现无法提交C++代码，想要退出比赛，说已提交过，无法退出。那么，就自己退出吧，让账号空悬在比赛中。

Codeforces Round #624 (Div. 3)   比赛人数6075

[codeforces 1311A] Add Odd or Subtract Even 奇+奇=偶,奇+偶=奇,偶+偶=偶

[codeforces 1311B] WeirdSort 冒泡排序

[codeforces 1311C] Perform the Combo 难懂的表述 逆向前缀和+int溢出

[codeforces 1311D] Three Integers 枚举所有可能+用约束降时间复杂度+一步分作两步走降时间复杂度

[codeforces 1311E] Construct the Binary Tree 一条路走到底 完全二叉树+链

[codeforces 1311F] Moving Points 离散化+树状数组

Codeforces Round #623 (Div. 2, based on VK Cup 2019-2020 - Elimination Round, Engine)   比赛人数3742

[codeforces 1315A] Dead Pixel 令人讨厌的行,列,横,纵,坐标 表格助阵

[codeforces 1315B] Homecoming 边写边调 找连续字母相同的子串

[codeforces 1315C] Restoring Permutation 比赛很锻炼人 做好最小匹配

[codeforces 1315D] Recommendations 大根堆

Codeforces Round #622 (Div. 2)   比赛人数5752

[codeforces 1313A] Fast Food Restaurant 生词太多

[codeforces 1313B] Different Rules 确实做不出

[codeforces 1313C1] Skyscrapers (easy version) 问的是谷，答的是峰

[codeforces 1313C2] Skyscrapers (hard version) 单调栈+变化量的和+俄罗斯方块

Codeforces Round #621 (Div. 1 + Div. 2)

[codeforces 1304A] Cow and Haybales 阴沟里翻船

[codeforces 1304B] Cow and Friend 除+模

[codeforces 1304C] Cow and Friend 26个字母中的某个字母前缀和+(26个字母中的某个字母)之前的(26个字母中的某个字母)的数量+int溢出

[codeforces 1304D] Cow and Fields 不只是最短路

Codeforces Round #620 (Div. 2)

[codeforces 1304A] Two Rabbits 整除+模

[codeforces 1304B] Longest Palindrome   distinct的教训

[codeforces 1304C] Air Conditioner 冗余的代码,意味着消耗+难点:必须所有数据读完,再处理

[codeforces 1304D] Shortest and Longest LIS 从极端结果出发进行演化

Codeforces Round #619 (Div. 2)

[codeforces 1301A] Three Strings 同一位上c元素与a或b元素相同,该位过关

[codeforces 1301B] Motarack's Birthday 找错了规律就完蛋

[codeforces 1301C] Ayoub's function 容斥原理+隔板法+等差数列求和

[codeforces 1301D] Time to Run 画图+周期性+你也可以

Educational Codeforces Round 82 (Rated for Div. 2)

[codeforces 1303A] Erasing Zeroes 标记1的位置+算出相邻1间0的个数

[codeforces 1303B] National Project 比赛中罕见多次说明+分类讨论+int溢出

[codeforces 1303C] Perfect Keyboard 写好一一映射f[x]=y,g[y]=x

[codeforces 1303D] Fill The Bag 位运算+巧妙的进退位

Codeforces Round #618 (Div. 2)

[codeforces 1300A] Non-zero (0+和)的处理

[codeforces 1300B] Assigning to Classes 排序+取中间两个数

[codeforces 1300C] Anu Has a Function 位运算+打表找规律+最高位开始同位中只有1个1的数摆第1个即可

[codeforces 1300D] Aerodynamic 几何+中心对称+非中心对称+(map,pair)查重+除法避免不整除的技巧

[codeforces 1300E] Water Balance 单调栈+斜率优化+前缀和

Codeforces Round #617 (Div. 3)

[codeforces 1296A] Array with Odd Sum 奇+奇=偶,奇+偶=奇,偶+偶=偶

[codeforces 1296B] Food Buying 找规律

[codeforces 1296C] Yet Another Walking Robot 三重排序+全网唯一的代码/STL中map+pair/类hash算法

[codeforces 1296D] Fight with Monsters 难在题意的理解+模+整除

[codeforces 1296E1] String Coloring (easy version) 当前字符必须加入+字典序

[codeforces 1296E2] String Coloring (hard version) 很牛的最长上升子序列的写法+还能记录子序列中的元素

[codeforces 1296F] Berland Beauty 难在题意的理解+树上暴力+map的耗时,可不是O(1)

Codeforces Round #616 (Div. 2)

[codeforces 1291A] Even But Not Even 奇+奇=偶,奇+偶=奇,偶+偶=偶
[codeforces 1291B] Array Sharpening 制造 上升数组;上升、下降数组;下降数组，进行对比，若能通过对比，则Yes,否则No

[codeforces 1291C] Mind Control 可控选最大+不可控选最小+有一点点象滑动窗口

[codeforces 1291D] Irreducible Anagrams 前缀和+aba的情况太难想了

Educational Codeforces Round 81 (Rated for Div. 2)

[codeforces 1295A] Display The Number 看起来挺吓人+整除+模

[codeforces 1295B] Infinite Prefixes 题目读起来有些费劲+周期性+特判+(%0+%负数+%正数)的讨论+比赛做出不易

[codeforces 1295C] Obtain The String 层层递进的dp(有一点点数字三角形的影子)

[codeforces 1295D] Same GCDs 欧拉函数

Codeforces Round #615 (Div. 3)

[codeforces 1294A] Collecting Coins 整除+不整除

[codeforces 1294B] Collecting Packages 排序+字符串

[codeforces 1294C] Product of Three Numbers 质数线性筛+质因数分解

[codeforces 1294D] MEX maximizing 模是最终归宿

Codeforces Round #614 (Div. 2)

[codeforces 1293A] ConneR and the A.R.C. Markland-N 不超时的二分/无限长数组map+桶排序

[codeforces 1293B] JOE is on TV! 1+1/2+1/3+1/4+......+1/n序列

[codeforces 1293C] NEKO's Maze Game 一个格子接着一个格子处理+滚动数组+画图思考

[codeforces 1293D] Aroma's Search 曼哈顿距离

Educational Codeforces Round 80 (Rated for Div. 2)

[codeforces 1288A] Deadline 约数+模

[codeforces 1288B] Yet Another Meme Problem 公式推导

[codeforces 1288C] Two Arrays 动归dp/多重集合的组合+快速幂+乘法逆元

[codeforces 1288D] Minimax Problem 状压+二分

[codeforces 1288E] Messenger Simulator 镜像+树状数组

Codeforces Round #613 (Div. 2)

[codeforces 1285A] Mezo Playing Zoma 字符串

[codeforces 1285B] Just Eat It! 最大连续子段和

[codeforces 1285C] Fadi and LCM 最大公约数+约数

[codeforces 1285D] Dr. Evil Underscores 不定长数组+分治算法+位运算

Codeforces Round #612 (Div. 2)

[codeforces 1287A] Angry Students 字符串
[codeforces 1287B] Hyperset 字符串+排序+二分

[codeforces 1287C] Garland 动归dp

[codeforces 1287D] Numbers on Tree 子树节点数

Hello 2020

[codeforces 1284A] New Year and Naming 字符串+模运算
[codeforces 1284B] New Year and Ascent Sequence 容斥原理+桶排序+前缀和+滚动数组

[codeforces 1284C] New Year and Permutation 组合数学

Codeforces Round #609 (Div. 2)

[codeforces 1269A] Equation 模拟
[codeforces 1269B] Modulo Equality 模拟
[codeforces 1269C] Long Beautiful Integer 字符串处理(类高精度加)
[codeforces 1269D] Domino for Young 棋盘的完美覆盖
[codeforces 1269E] K Integers 逆序对+平移+树状数组+二分

Codeforces Round #608 (Div. 2)
[codeforces 1271A] Suits 模拟
[codeforces 1271B] Blocks 模拟
[codeforces 1271C] Shawarma Tent 模拟(曼哈顿距离)
[codeforces 1271D] Portals 反悔贪心算法
[codeforces 1271E] Common Number 打表+找规律

Codeforces Round #607 (Div. 2)
[codeforces 1281A] Suffix Three 字符串+模拟

[codeforces 1281B] Azamon Web Services 字符串+strcmp时间复杂度理解

Codeforces Round #606 (Div. 2, based on Technocup 2020 Elimination Round 4)
[codeforces 1277A] Happy Birthday, Polycarp! 模拟
[codeforces 1277B] Make Them Odd 模拟