這些年打過的比賽codeforces

這些年打過的比賽codeforces

Codeforces Round #653 (Div. 3)   參與排名人數11687

[codeforces 1374A] Required Remainder 帶餘除法(該詞來自初等數論)

[codeforces 1374B] Multiply by 2, divide by 6 統計3的冪次+統計2的冪次

[codeforces 1374C] Move Brackets 括號()配對

[codeforces 1374D] Zero Remainder Array 跳躍補缺

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

[codeforces 1374F] Cyclic Shifts Sorting 按規則先排最小再排最大

Educational Codeforces Round 90 (Rated for Div. 2)   參與排名人數12840

[codeforces 1373A] Donut Shops 選一個還是選一堆

[codeforces 1373B] 01 Game 刪除01或10的博弈

[codeforces 1373C] Pluses and Minuses 找規律,難在+號會使數據發生跳躍,跳過了中間的+號

[codeforces 1373D] Maximum Sum on Even Positions 翻轉不改變相對位置+兩種交換形式

[codeforces 1373E] Sum of Digits 十位數百位數乃至更高位的進位不可能發生

Codeforces Round #652 (Div. 2)   參與排名人數14647

[codeforces 1369A] FashionabLee 正多邊形

[codeforces 1369B] AccurateLee 尋找左邊界的1,右邊界的0

[codeforces 1369C] RationalLee 自大到小分配+自少向多分配+不定長數組的使用

[codeforces 1369D] TediousLee 樹上找規律

Codeforces Round #651 (Div. 2)  參與排名人數14559

[codeforces 1370A] Maximum GCD 找n/2的值

[codeforces 1370B] GCD Compression 構造共有因子爲2的數組集合

[codeforces 1370C] Number Game 質因數分解+坑點賊多

[codeforces 1370D] Odd-Even Subsequence 二分查找+跳躍取數

[codeforces 1370E] Binary Subsequence Rotation 兩種旋轉形式

Codeforces Global Round 8  參與排名人數13404

[codeforces 1368A] C+= 斐波那契數列+數據範圍有誤

[codeforces 1368B] Codeforces Subsequences 乘法原理

[codeforces 1368C] Even Picture 階梯式的構造

[codeforces 1368D] AND, OR and square sum 操作過後各個位上1的數量竟然不變

Codeforces Round #650 (Div. 3)  參與排名人數11978

[codeforces 1367A] Short Substrings 間隔取字符

[codeforces 1367B] Even Array 統計餘數情況

[codeforces 1367C] Social Distance 判定連續的k個數是0

[codeforces 1367D] Task On The Board 設置位置的優先級

[codeforces 1367E] Necklace Assembly 根據週期進行分塊,每塊相應位置的字母都需雷同

Codeforces Round #649 (Div. 2)  參與排名人數11286

[codeforces 1364A] XXXXX 餘數的拆分

[codeforces 1364B] Most socially-distanced subsequence 絕對值脫殼的4種形態

[codeforces 1364C] Ehab and Prefix MEXs MEX數據生成

Educational Codeforces Round 89 (Rated for Div. 2)  參與排名人數13281

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

[codeforces 1366B] Shuffle 區間交疊+區間合併

[codeforces 1366C] Palindromic Paths 將值需相同的位置找出，統計其中0,1個數

[codeforces 1366D] Two Divisors 互質公式推導+線性篩素數

[codeforces 1366E] Two Arrays 雙指針+乘法原理+注意邊界處理

Codeforces Round #648 (Div. 2)  參與排名人數13231

[codeforces 1365A] Matrix Game 管住行守住列

[codeforces 1365B] Trouble Sort 只要存在b[i]!=b[j],就一定能換成最後的非遞減序列

[codeforces 1365C] Rotation Matching 尋找偏移量

[codeforces 1365D] Solve The Maze 遍歷矩陣的深搜dfs+隔斷的設置

[codeforces 1365E] Maximum Subsequence Value 或運算+爲什麼選三個元素對應最大值

[codeforces 1365F] Swaps Again 以不變應萬變

Codeforces Round #647 (Div. 2) - Thanks, Algo Muse!  參與排名人數12044

[codeforces 1362A] Johnny and Ancient Computer 倍數關係用2的冪次統計

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

[codeforces 1362C] Johnny and Another Rating Drop 打表+按位找規律

[codeforces 1362D] Johnny and Contribution 驗證拓撲排序

[codeforces 1362E] Johnny and Grandmaster p進制

Codeforces Round #646 (Div. 2)  參與排名人數14203

[codeforces 1363A] Odd Selection 偶數不夠奇數來補

[codeforces 1363B] Subsequence Hate 最終有4種形態+前綴和

[codeforces 1363C] Game On Leaves 樹上分勝負

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

[codeforces 1363E] Tree Shuffling 可以迴避排序的樹上結構(鏈式結構不超時的寫法)

Educational Codeforces Round 88 (Rated for Div. 2)  參賽人數19992

[codeforces 1359A] Berland Poker 抽屜原理

[codeforces 1359B] New Theatre Square 2塊對應的數量統計

[codeforces 1359C] Mixing Water 公式推導+浮點數化整數+絕對值脫殼的4種形態

[codeforces 1359D] Yet Another Yet Another Task 當前元素爲峯值進行蠶食

[codeforces 1359E] Modular Stability 快速冪+乘法逆元+組合數計算+找規律

Codeforces Round #645 (Div. 2)  參與排名人數14819

[codeforces 1358A] Park Lighting 向上取整

[codeforces 1358B] Maria Breaks the Self-isolation 叫上所有夥伴 (自小到大排序+逆序處理)

[codeforces 1358C] Celex Update 找規律+猜公式

[codeforces 1358D] The Best Vacation 有個數限制的最大連續子段和

Codeforces Round #644 (Div. 3)  參賽人數20688

[codeforces 1360A] Minimal Square 關鍵詞identical

[codeforces 1360B] Honest Coach 排序+找相鄰差值最小的兩個數

[codeforces 1360C] Similar Pairs 坑點較多

[codeforces 1360D] Buying Shovels 在指定範圍內找最大約數

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

[codeforces 1360F] Spy-string 難想的爆搜

[codeforces 1360G] A/B Matrix 橫豎都一樣+緊湊排列

Educational Codeforces Round 87 (Rated for Div. 2)  參與排名人數11499,比賽前遇到2次延時,17:05-17:15,17:15-17:20

[codeforces 1354A] Alarm Clock 難在題意的解讀

[codeforces 1354B] Ternary String 尋找6種組合

[codeforces 1354C1] Simple Polygon Embedding 找外接圓

[codeforces 1354C2] Not So Simple Polygon Embedding 幾何畫板

[codeforces 1354D] Multiset 線段樹(由數值找節點位置,由排名找節點位置)

Codeforces Round #643 (Div. 2)  參與排名人數11475

[codeforces 1355A] Sequence with Digits 十進制轉換+打表找規律

[codeforces 1355B] Young Explorers 題意難懂

[codeforces 1355C] Count Triangles 公式推導+找規律+雙指針+排列組合中的乘法原理

[codeforces 1355D] Game With Array 極端的構造

Codeforces Round #642 (Div. 3)  參與排名人數11823

[codeforces 1353A] Most Unstable Array 照着葫蘆畫瓢

[codeforces 1353B] Two Arrays And Swaps 若數組a中最小值小於b中最大值，將其用b中最大值替換

[codeforces 1353C] Board Moves 畫圖找規律

[codeforces 1353D] Constructing the Array 分治算法

[codeforces 1353E] K-periodic Garland 爲什麼會想到動歸dp

Codeforces Round #641 (Div. 2)   參與排名人數11937

[codeforces 1350A] Orac and Factors 找規律

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

[codeforces 1350C] Orac and LCM 最大公約數+最小公倍數+公式推導

[codeforces 1350D] Orac and Medians 在連續串(串長爲2或3)中找2個大於等於k的元素

Codeforces Round #640 (Div. 4)   參與排名人數9749,終於弄明白賬號前*的意義,*out of competition,也即雖然該用戶參加本場比賽,但不參與排名。

[codeforces 1352A] Sum of Round Numbers 十進制轉換

[codeforces 1352B] Same Parity Summands 奇數偶數二選一

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

[codeforces 1352D] Alice, Bob and Candies 每人兩個指針+前綴和

[codeforces 1352E] Special Elements 桶排序+前綴和

[codeforces 1352F] Binary String Reconstruction 先處理00,再處理11,最後處理(01或10)

[codeforces 1352G] Special Permutation 構造偶數序列,奇數序列,合併

Testing Round #16 (Unrated)   測試人數4695

[codeforces 1351A] A+B (Trial Problem) 加法運算

[codeforces 1351B] Square? 拼接成正方形

[codeforces 1351C] Skier 區分出不同位置+連成圖+找重邊/map+pair的寫法/set+pair的寫法

Codeforces Round #639 (Div. 2)   5月3日,正要開打前5分鐘,來了句Codeforces Round #639: the round is rescheduled,5月6日開打，遇到了測試要排長長的隊伍(印象中IOI比賽是這樣),抓狂,唯一慰藉的是,此場Unrated。   比賽人數13765

[codeforces 1345A] Puzzle Pieces 注意one blank

[codeforces 1345B] Card Constructions 找規律

[codeforces 1345C] Hilbert's Hotel 找規律+週期+轉圈圈(模)

Codeforces Round #638 (Div. 2)  比賽人數15215

[codeforces 1348A] Phoenix and Balance 一個頂倆

[codeforces 1348B] Phoenix and Beauty 找週期

[codeforces 1348C] Phoenix and Distribution 5種形態

[codeforces 1348D] Phoenix and Science 從兩個極端結果出發,找到中間結果

Educational Codeforces Round 86 (Rated for Div. 2)  比賽人數15356

[codeforces 1342A] Road To Zero 兩種選擇有優劣

[codeforces 1342B] Binary Period 週期要麼是1要麼是2

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

[codeforces 1342D] Multiple Testcases 均勻安置

[codeforces 1342E] Placing Rooks 容斥原理

Codeforces Round #637 (Div. 2) - Thanks, Ivan Belonogov!   比賽人數15390

[codeforces 1341A] Nastya and Rice 區間交疊

[codeforces 1341B] Nastya and Door 神奇的掐頭去尾+前綴和

[codeforces 1341C] Nastya and Strange Generator 讓人鬱悶的題

[codeforces 1341D] Nastya and Scoreboard 二進制運算+布爾揹包

Codeforces Round #636 (Div. 3)   比賽人數12253

[codeforces 1343A] Candies 等比數列求和公式

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

[codeforces 1343C] Alternating Subsequence 在連續負數或正數區間內找最大值

[codeforces 1343D] Constant Palindrome Sum 尋找需改變區間的邊界+前綴和

[codeforces 1343E] Weights Distributing SPFA+中轉的路徑

[codeforces 1343F] Restore the Permutation by Sorted Segments 從假定出發的嘗試

Codeforces Round #635 (Div. 2)   比賽人數14830

[codeforces 1337A] Ichihime and Triangle 兩邊之和大於第三邊

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

[codeforces 1337C] Linova and Kingdom 公式推導

[codeforces 1337D] Xenia and Colorful Gems 尋找6種組合

[codeforces 1337E] Kaavi and Magic Spell 區間動歸dp

[codeforces 1337F] Yui and Mahjong Set 公式推導+交互式程序的測試

Codeforces Round #634 (Div. 3)   比賽人數11922  慢慢的對Div. 3難度有了些感覺

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

[codeforces 1335B] Construct the String b代表週期

[codeforces 1335C] Two Teams Composing 統計技能種類數量+統計同一技能最大數量

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

[codeforces 1335E1] Three Blocks Palindrome (easy version) 分成左中右3個區間+前綴和

[codeforces 1335E2] Three Blocks Palindrome (hard version) 從中間位置向兩邊擴散

[codeforces 1335F] Robots on a Grid 倍增

Codeforces Round #633 (Div. 2)   比賽人數12032  打完atcoder還沒歇腳，緊接着就是codeforces

[codeforces 1339A] Filling Diamonds 給我一張有圖的紙

[codeforces 1339B] Sorted Adjacent Differences 排序後將數據分組,合併

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

Educational Codeforces Round 85 (Rated for Div. 2)   比賽人數14824

[codeforces 1334A] Level Statistics 坑點較多

[codeforces 1334B] Middle Class 多退少補

[codeforces 1334C] Circle of Monsters 公式推導+變環形關係爲直線關係+前綴和

[codeforces 1334D] Minimum Euler Cycle 找規律

Codeforces Round #632 (Div. 2)   比賽人數12810

[codeforces 1333A] Little Artem 讀懂題+找規律+多舉例

[codeforces 1333B] Kind Anton 統計區間0,1,-1出現的情況

[codeforces 1333C] Eugene and an array 尋找位置i所轄的最遠位置

[codeforces 1333D] Challenges in school №41 在整體移動中,記錄個體移動的信息

[codeforces 1333E] Road to 1600 構造+蛇形

[codeforces 1333F] Kate and imperfection 先加入所有質數,再加入最大約數爲２的數,緊接着加入最大約數爲３的數,以此類推

Codeforces Round #631 (Div. 1) - Thanks, Denis aramis Shitov!   比賽人數1273

 

Codeforces Round #631 (Div. 2) - Thanks, Denis aramis Shitov!   比賽人數10889

[codeforces 1330A] Dreamoon and Ranking Collection 連續遞增序列判定

[codeforces 1330B] Dreamoon Likes Permutations 合理分塊

[codeforces 1330C] Dreamoon Likes Coloring 極端處理,再圖變通

[codeforces 1330D] Dreamoon Likes Sequences 數據分組+乘法原理

[codeforces 1330E] Drazil Likes Heap 堆元素刪除+堆深度+貪心

April Fools Day Contest 2020   真的是愚人節的題目，好吧，不打了，睡覺去了

Codeforces Round #630 (Div. 2)   比賽人數12012

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

[codeforces 1332B] Composite Coloring 不超過11種顏色的證明

[codeforces 1332C] K-Complete Word 切割成k長子串,在子串中,根據中心對稱,保留數量最多的字母

[codeforces 1332D] Walk on Matrix 構造

[codeforces 1332E] Height All the Same 奇偶構造+排列組合+快速冪+二項式定理+乘法逆元

Codeforces Round #629 (Div. 3)   比賽人數10967

[codeforces 1328A] Divisibility Problem 整除+模

[codeforces 1328B] K-th Beautiful String 研究倒數第二個字母b的位置

[codeforces 1328C] Ternary XOR 題意易懂,但不好編

[codeforces 1328D] Carousel 分類討論

Educational Codeforces Round 84 (Rated for Div. 2)   比賽人數13522

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

[codeforces 1327B] Princesses and Princes 過長的題目+難懂的題意

[codeforces 1327C] Game with Chips 有點象飛行棋

[codeforces 1327E] Count The Blocks 打表找規律+根據規律找公式+優化公式

Codeforces Global Round 7   比賽人數10630

[codeforces 1326A] Bad Ugly Numbers 構造由2,3,4組成的不能被3整除的奇數

[codeforces 1326B] Maximums 公式推導

[codeforces 1326C] Permutation Partitions 排列組合

[codeforces 1326D1] Prefix-Suffix Palindrome (Easy version) 首尾迴文+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 馬拉車算法

Codeforces Round #628 (Div. 2)   比賽人數9400

[codeforces 1325A] EhAb AnD gCd 公式推導

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

[codeforces 1325C] Ehab and Path-etic MEXs 繞不開的葉節點+特判

[codeforces 1325D] Ehab the Xorcist 異或+難點是最小個數

Codeforces Round #627 (Div. 3)   比賽人數6434

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

[codeforces 1324B] Yet Another Palindrome Problem 迴文+邊界處理

[codeforces 1324C] Frog Jumps 一直向右+邊界處理

[codeforces 1324D] Pair of Topics 分而治之+排列組合

Educational Codeforces Round 83 (Rated for Div. 2)   比賽人數8705

[codeforces 1312A] Two Regular Polygons 整除

[codeforces 1312B] Bogosort 逆序證明

[codeforces 1312C] Adding Powers 進制轉換

[codeforces 1312D] Count the Arrays 排列組合+快速冪+乘法逆元+二項式定理

Codeforces Round #626 (Div. 2, based on Moscow Open Olympiad in Informatics)   比賽人數5260

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

[codeforces 1323B] Count Subrectangles 分而治之+細節較多

[codeforces 1323C] Unusual Competitions 棧呼之欲出

CodeCraft-20 (Div. 2)   比賽人數7369

[codeforces 1316A] Grade Allocation 熱身

[codeforces 1316B] String Modification 力挽狂瀾

[codeforces 1316C] Primitive Primes 絕殺

Ozon Tech Challenge 2020 (Div.1 + Div.2, Rated, T-shirts + prizes!)   比賽人數7420

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

[codeforces 1305B] Kuroni and Simple Strings 有點象快排

[codeforces 1305C] Kuroni and Impossible Calculation 數據範圍是突破

Codeforces Round #625 (Div. 2, based on Technocup 2020 Final Round)   比賽人數5638

[codeforces 1321A] Contest for Robots 題目有些長

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

[codeforces 1321C] Remove Adjacent 從字典序最大的字母開始處理

[codeforces 1321D] Navigation System 逆向最短路+題意解讀

Kotlin Heroes: Episode 3   比賽人數912

快速做完第一題，迅速提交，編譯錯誤，好吧，再提交一遍，說是提交雷同代碼，無法提交，定睛一看，編譯語言是Kotlin

上下尋找，發現無法提交C++代碼，想要退出比賽，說已提交過，無法退出。那麼，就自己退出吧，讓賬號空懸在比賽中。

Codeforces Round #624 (Div. 3)   比賽人數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 難懂的表述 逆向前綴和+int溢出

[codeforces 1311D] Three Integers 枚舉所有可能+用約束降時間複雜度+一步分作兩步走降時間複雜度

[codeforces 1311E] Construct the Binary Tree 一條路走到底 完全二叉樹+鏈

[codeforces 1311F] Moving Points 離散化+樹狀數組

Codeforces Round #623 (Div. 2, based on VK Cup 2019-2020 - Elimination Round, Engine)   比賽人數3742

[codeforces 1315A] Dead Pixel 令人討厭的行,列,橫,縱,座標 表格助陣

[codeforces 1315B] Homecoming 邊寫邊調 找連續字母相同的子串

[codeforces 1315C] Restoring Permutation 比賽很鍛鍊人 做好最小匹配

[codeforces 1315D] Recommendations 大根堆

Codeforces Round #622 (Div. 2)   比賽人數5752

[codeforces 1313A] Fast Food Restaurant 生詞太多

[codeforces 1313B] Different Rules 確實做不出

[codeforces 1313C1] Skyscrapers (easy version) 問的是谷，答的是峯

[codeforces 1313C2] Skyscrapers (hard version) 單調棧+變化量的和+俄羅斯方塊

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

[codeforces 1304A] Cow and Haybales 陰溝裏翻船

[codeforces 1304B] Cow and Friend 除+模

[codeforces 1304C] Cow and Friend 26個字母中的某個字母前綴和+(26個字母中的某個字母)之前的(26個字母中的某個字母)的數量+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的教訓

[codeforces 1304C] Air Conditioner 冗餘的代碼,意味着消耗+難點:必須所有數據讀完,再處理

[codeforces 1304D] Shortest and Longest LIS 從極端結果出發進行演化

Codeforces Round #619 (Div. 2)

[codeforces 1301A] Three Strings 同一位上c元素與a或b元素相同,該位過關

[codeforces 1301B] Motarack's Birthday 找錯了規律就完蛋

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

[codeforces 1301D] Time to Run 畫圖+週期性+你也可以

Educational Codeforces Round 82 (Rated for Div. 2)

[codeforces 1303A] Erasing Zeroes 標記1的位置+算出相鄰1間0的個數

[codeforces 1303B] National Project 比賽中罕見多次說明+分類討論+int溢出

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

[codeforces 1303D] Fill The Bag 位運算+巧妙的進退位

Codeforces Round #618 (Div. 2)

[codeforces 1300A] Non-zero (0+和)的處理

[codeforces 1300B] Assigning to Classes 排序+取中間兩個數

[codeforces 1300C] Anu Has a Function 位運算+打表找規律+最高位開始同位中只有1個1的數擺第1個即可

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

[codeforces 1300E] Water Balance 單調棧+斜率優化+前綴和

Codeforces Round #617 (Div. 3)

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

[codeforces 1296B] Food Buying 找規律

[codeforces 1296C] Yet Another Walking Robot 三重排序+全網唯一的代碼/STL中map+pair/類hash算法

[codeforces 1296D] Fight with Monsters 難在題意的理解+模+整除

[codeforces 1296E1] String Coloring (easy version) 當前字符必須加入+字典序

[codeforces 1296E2] String Coloring (hard version) 很牛的最長上升子序列的寫法+還能記錄子序列中的元素

[codeforces 1296F] Berland Beauty 難在題意的理解+樹上暴力+map的耗時,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 製造 上升數組;上升、下降數組;下降數組，進行對比，若能通過對比，則Yes,否則No

[codeforces 1291C] Mind Control 可控選最大+不可控選最小+有一點點象滑動窗口

[codeforces 1291D] Irreducible Anagrams 前綴和+aba的情況太難想了

Educational Codeforces Round 81 (Rated for Div. 2)

[codeforces 1295A] Display The Number 看起來挺嚇人+整除+模

[codeforces 1295B] Infinite Prefixes 題目讀起來有些費勁+週期性+特判+(%0+%負數+%正數)的討論+比賽做出不易

[codeforces 1295C] Obtain The String 層層遞進的dp(有一點點數字三角形的影子)

[codeforces 1295D] Same GCDs 歐拉函數

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 質數線性篩+質因數分解

[codeforces 1294D] MEX maximizing 模是最終歸宿

Codeforces Round #614 (Div. 2)

[codeforces 1293A] ConneR and the A.R.C. Markland-N 不超時的二分/無限長數組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 一個格子接着一個格子處理+滾動數組+畫圖思考

[codeforces 1293D] Aroma's Search 曼哈頓距離

Educational Codeforces Round 80 (Rated for Div. 2)

[codeforces 1288A] Deadline 約數+模

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

[codeforces 1288C] Two Arrays 動歸dp/多重集合的組合+快速冪+乘法逆元

[codeforces 1288D] Minimax Problem 狀壓+二分

[codeforces 1288E] Messenger Simulator 鏡像+樹狀數組

Codeforces Round #613 (Div. 2)

[codeforces 1285A] Mezo Playing Zoma 字符串

[codeforces 1285B] Just Eat It! 最大連續子段和

[codeforces 1285C] Fadi and LCM 最大公約數+約數

[codeforces 1285D] Dr. Evil Underscores 不定長數組+分治算法+位運算

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 動歸dp

[codeforces 1287D] Numbers on Tree 子樹節點數

Hello 2020

[codeforces 1284A] New Year and Naming 字符串+模運算
[codeforces 1284B] New Year and Ascent Sequence 容斥原理+桶排序+前綴和+滾動數組

[codeforces 1284C] New Year and Permutation 組合數學

Codeforces Round #609 (Div. 2)

[codeforces 1269A] Equation 模擬
[codeforces 1269B] Modulo Equality 模擬
[codeforces 1269C] Long Beautiful Integer 字符串處理(類高精度加)
[codeforces 1269D] Domino for Young 棋盤的完美覆蓋
[codeforces 1269E] K Integers 逆序對+平移+樹狀數組+二分

Codeforces Round #608 (Div. 2)
[codeforces 1271A] Suits 模擬
[codeforces 1271B] Blocks 模擬
[codeforces 1271C] Shawarma Tent 模擬(曼哈頓距離)
[codeforces 1271D] Portals 反悔貪心算法
[codeforces 1271E] Common Number 打表+找規律

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

[codeforces 1281B] Azamon Web Services 字符串+strcmp時間複雜度理解

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