Problem ID stringlengths 2 6 | Problem Description stringlengths 0 7.52k | Rating float64 800 3.5k | math bool 2
classes | greedy bool 2
classes | implementation bool 2
classes | dp bool 2
classes | data structures bool 2
classes | constructive algorithms bool 2
classes | brute force bool 2
classes | binary search bool 2
classes | sortings bool 2
classes | graphs bool 2
classes | __index_level_0__ int64 3 9.98k |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
222E | Recently a top secret mission to Mars has taken place. As a result, scientists managed to obtain some information about the Martian DNA. Now we know that any Martian DNA contains at most _m_ different nucleotides, numbered from 1 to _m_. Special characteristics of the Martian DNA prevent some nucleotide pairs from foll... | 1,900 | false | false | false | true | false | false | false | false | false | false | 8,948 |
1988B | You are given a sequence $$$[a_1,ldots,a_n]$$$ where each element $$$a_i$$$ is either $$$0$$$ or $$$1$$$. You can apply several (possibly zero) operations to the sequence. In each operation, you select two integers $$$1le lle rle a$$$ (where $$$a$$$ is the current length of $$$a$$$) and replace $$$[a_l,ldots,a_r]$$$ wi... | 900 | false | true | true | false | false | false | false | false | false | false | 346 |
850B | Arpa has found a list containing _n_ numbers. He calls a list bad if and only if it is not empty and gcd (see notes section for more information) of numbers in the list is 1. Arpa can perform two types of operations: Choose a number and delete it with cost _x_. Choose a number and increase it by 1 with cost _y_. Arpa... | 2,100 | false | false | true | false | false | false | false | false | false | false | 6,350 |
246C | General Payne has a battalion of _n_ soldiers. The soldiers' beauty contest is coming up, it will last for _k_ days. Payne decided that his battalion will participate in the pageant. Now he has choose the participants. All soldiers in the battalion have different beauty that is represented by a positive integer. The va... | 1,600 | false | true | false | false | false | true | true | false | false | false | 8,846 |
538A | A large banner with word CODEFORCES was ordered for the 1000-th onsite round of Codeforcesω that takes place on the Miami beach. Unfortunately, the company that made the banner mixed up two orders and delivered somebody else's banner that contains someone else's word. The word on the banner consists only of upper-case ... | 1,400 | false | false | true | false | false | false | true | false | false | false | 7,688 |
845G | Problem - 845G - Codeforces =============== xa0 . You have to find the minimum length of path between vertex 1 and vertex _n_. Note that graph can contain multiple edges and loops. It is guaranteed that the graph is connected. Input The first line contains two numbers _n_ and _m_ (1u2009≤u2009_n_u2009≤u20... | 2,300 | true | false | false | false | false | false | false | false | false | true | 6,378 |
1608F | Problem - 1608F - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - ... | 3,200 | false | false | true | true | false | false | false | false | false | false | 2,610 |
1735D | You like the card board game "Set". Each card contains $$$k$$$ features, each of which is equal to a value from the set $$${0, 1, 2}$$$. The deck contains all possible variants of cards, that is, there are $$$3^k$$$ different cards in total. A feature for three cards is called good if it is the same for these cards or ... | 1,700 | true | false | false | false | true | false | true | false | false | false | 1,877 |
763A | Each New Year Timofey and his friends cut down a tree of _n_ vertices and bring it home. After that they paint all the _n_ its vertices, so that the _i_-th vertex gets color _c__i_. Now it's time for Timofey birthday, and his mother asked him to remove the tree. Timofey removes the tree in the following way: he takes s... | 1,600 | false | false | true | true | false | false | false | false | false | true | 6,737 |
685B | After the piece of a devilish mirror hit the Kay's eye, he is no longer interested in the beauty of the roses. Now he likes to watch snowflakes. Once upon a time, he found a huge snowflake that has a form of the tree (connected acyclic graph) consisting of _n_ nodes. The root of tree has index 1. Kay is very interested... | 1,900 | false | false | false | true | true | false | false | false | false | false | 7,082 |
1556D | Enter Register HOME TOP CATALOG CONTESTS GYM PROBLEMSET GROUPS RATING EDU API CALENDAR HELP RAYAN Deltix Round, Summer 2021 (open for everyone, rated, Div. 1 + Div. 2) Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported... | 1,800 | true | false | false | false | false | true | false | false | false | false | 2,852 |
190E | Berland has managed to repel the flatlanders' attack and is now starting the counter attack. Flatland has _n_ cities, numbered from 1 to _n_, and some pairs of them are connected by bidirectional roads. The Flatlandian maps show roads between cities if and only if there is in fact no road between this pair of cities (w... | 2,100 | false | false | false | false | true | false | false | false | true | true | 9,078 |
245H | Problem - 245H - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,800 | false | false | false | true | false | false | false | false | false | false | 8,849 |
870A | Problem - 870A - Codeforces =============== xa0 ") ") representation has at least one digit from the first list and at least one digit from the second list. What is the smallest positive pretty integer? Input The first line contains two integers _n_ and _m_ (1u2009≤u2009_n_,u2009_m_u2009≤u20099) — the leng... | 900 | false | false | true | false | false | false | true | false | false | false | 6,261 |
174A | A group of _n_ merry programmers celebrate Robert Floyd's birthday. Polucarpus has got an honourable task of pouring Ber-Cola to everybody. Pouring the same amount of Ber-Cola to everybody is really important. In other words, the drink's volume in each of the _n_ mugs must be the same. Polycarpus has already began the ... | 1,100 | true | false | false | false | false | false | false | false | false | false | 9,168 |
463D | Problem - 463D - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,900 | false | false | true | true | false | false | false | false | false | true | 7,986 |
358B | Seryozha has a very changeable character. This time he refused to leave the room to Dima and his girlfriend (her hame is Inna, by the way). However, the two lovebirds can always find a way to communicate. Today they are writing text messages to each other. Dima and Inna are using a secret code in their text messages. W... | 1,500 | false | false | false | false | false | false | true | false | false | false | 8,403 |
373A | Cucumber boy is fan of Kyubeat, a famous music game. Kyubeat has 16 panels for playing arranged in 4u2009×u20094 table. When a panel lights up, he has to press that panel. Each panel has a timing to press (the preffered time when a player should press it), and Cucumber boy is able to press at most _k_ panels in a time ... | 900 | false | false | true | false | false | false | false | false | false | false | 8,338 |
522D | Problem - 522D - Codeforces =============== xa0 ]( "VK Cup 2015 — Квалификация 1") . For each query you need to print the minimum distance between such pair of elements _a__x_ and _a__y_ (_x_u2009≠u2009_y_), that: both indexes of the elements lie within range | 2,000 | false | false | false | false | true | false | false | false | false | false | 7,747 |
414E | After a lot of trying, Mashmokh designed a problem and it's your job to solve it. You have a tree _T_ with _n_ vertices. Each vertex has a unique index from 1 to _n_. The root of _T_ has index 1. For each vertex of this tree _v_, you are given a list of its children in a specific order. You must perform three types of ... | 3,200 | false | false | false | false | true | false | false | false | false | false | 8,165 |
939E | Problem - 939E - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,800 | false | true | false | false | false | false | false | true | false | false | 5,940 |
2013B | Eralim, being the mafia boss, manages a group of $$$n$$$ fighters. Fighter $$$i$$$ has a rating of $$$a_i$$$. Eralim arranges a tournament of $$$n - 1$$$ battles, in each of which two not yet eliminated fighters $$$i$$$ and $$$j$$$ ($$$1 le i < j le n$$$) are chosen, and as a result of the battle, fighter $$$i$$$ is el... | 900 | true | true | false | false | false | true | false | false | false | false | 177 |
235D | In computer science, there is a method called "Divide And Conquer By Node" to solve some hard problems about paths on a tree. Let's desribe how this method works by function: _solve_(_t_) (_t_ is a tree): 1. Chose a node _x_ (it's common to chose weight-center) in tree _t_. Let's call this step "Line A". 2. Deal with a... | 3,000 | false | false | false | false | false | false | false | false | false | true | 8,893 |
1148G | Consider an undirected graph $$$G$$$ with $$$n$$$ vertices. There is a value $$$a_i$$$ in each vertex. Two vertices $$$i$$$ and $$$j$$$ are connected with an edge if and only if $$$gcd(a_i, a_j) > 1$$$, where $$$gcd(x, y)$$$ denotes the where all vertices are fair or all vertices are not fair. One can show that such a ... | 3,300 | true | false | false | false | false | true | false | false | false | true | 4,971 |
1427D | You are given a deck of $$$n$$$ cards numbered from $$$1$$$ to $$$n$$$ (not necessarily in this order in the deck). You have to sort the deck by repeating the following operation. Choose $$$2 le k le n$$$ and split the deck in $$$k$$$ nonempty contiguous parts $$$D_1, D_2,dots, D_k$$$ ($$$D_1$$$ contains the first $$$... | 2,000 | false | false | true | false | false | true | false | false | false | false | 3,530 |
747F | Problem - 747F - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 2,500 | true | false | false | true | false | false | true | false | false | false | 6,805 |
1418E | You are playing a computer game. In this game, you have to fight $$$n$$$ monsters. To defend from monsters, you need a shield. Each shield has two parameters: its current durability $$$a$$$ and its defence rating $$$b$$$. Each monster has only one parameter: its strength $$$d$$$. When you fight a monster with strength ... | 2,400 | false | false | false | false | false | false | false | true | false | false | 3,590 |
1428F | Zookeeper is buying a carton of fruit to feed his pet wabbit. The fruits are a sequence of apples and oranges, which is represented by a binary string $$$s_1s_2ldots s_n$$$ of length $$$n$$$. $$$1$$$ represents an apple and $$$0$$$ represents an orange. Since wabbit is allergic to eating oranges, Zookeeper would like t... | 2,400 | false | false | false | true | true | false | false | true | false | false | 3,520 |
819E | Problem - 819E - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 2,800 | false | false | false | false | false | true | false | false | false | true | 6,476 |
765D | Problem - 765D - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,700 | true | false | false | false | false | true | false | false | false | false | 6,727 |
322A | Problem - 322A - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,000 | false | true | false | false | false | false | false | false | false | false | 8,546 |
641E | Little Artem has invented a time machine! He could go anywhere in time, but all his thoughts of course are with computer science. He wants to apply this time machine to a well-known data structure: multiset. Artem wants to create a basic multiset of integers. He wants these structure to support operations of three type... | 2,000 | false | false | false | false | true | false | false | false | false | false | 7,247 |
1136A | After lessons Nastya decided to read a book. The book contains $$$n$$$ chapters, going one after another, so that one page of the book belongs to exactly one chapter and each chapter contains at least one page. Yesterday evening Nastya did not manage to finish reading the book, so she marked the page with number $$$k$$... | 800 | false | false | true | false | false | false | false | false | false | false | 5,047 |
1409F | You are given two strings $$$s$$$ and $$$t$$$ consisting of lowercase Latin letters. The length of $$$t$$$ is $$$2$$$ (i.e. this string consists only of two characters). In one move, you can choose any character of $$$s$$$ and replace it with any lowercase Latin letter. More formally, you choose some $$$i$$$ and replac... | 2,100 | false | false | false | true | false | false | false | false | false | false | 3,622 |
2039C2 | This is the hard version of the problem. The differences between the two versions are highlighted in bold. You can only make hacks if both versions of the problem are solved. Shohag has two integers $$$x$$$ and $$$m$$$. Help him count the number of integers $$$1 le y le m$$$ such that $$$x oplus y$$$ is divisible$$$^{ ... | 1,800 | true | false | false | false | false | false | true | false | false | false | 21 |
1353C | You are given a board of size $$$n imes n$$$, where $$$n$$$ is odd (not divisible by $$$2$$$). Initially, each cell of the board contains one figure. In one move, you can select exactly one figure presented in some cell and move it to one of the cells sharing a side or a corner with the current cell, i.e. from the cel... | 1,000 | true | false | false | false | false | false | false | false | false | false | 3,943 |
405C | Little Chris is a huge fan of linear algebra. This time he has been given a homework about the unusual square of a square matrix. The dot product of two integer number vectors _x_ and _y_ of size _n_ is the sum of the products of the corresponding components of the vectors. The unusual square of an _n_u2009×u2009_n_ sq... | 1,600 | true | false | true | false | false | false | false | false | false | false | 8,203 |
1260B | You are given two integers $$$a$$$ and $$$b$$$. You may perform any number of operations on them (possibly zero). During each operation you should choose any positive integer $$$x$$$ and set $$$a := a - x$$$, $$$b := b - 2x$$$ or $$$a := a - 2x$$$, $$$b := b - x$$$. Note that you may choose different values of $$$x$$$ ... | 1,300 | true | false | false | false | false | false | false | true | false | false | 4,393 |
1365G | 2,800 | true | false | false | false | false | true | false | false | false | false | 3,851 | |
300B | A programming coach has _n_ students to teach. We know that _n_ is divisible by 3. Let's assume that all students are numbered from 1 to _n_, inclusive. Before the university programming championship the coach wants to split all students into groups of three. For some pairs of students we know that they want to be on t... | 1,500 | false | false | false | false | false | false | true | false | false | true | 8,634 |
1666C | Problem - 1666C - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - ... | 1,800 | false | false | false | false | false | true | true | false | false | false | 2,283 |
1805D | You are given a tree (a connected graph without cycles) with $$$n$$$ vertices. Consider a fixed integer $$$k$$$. Then, the graph $$$G_k$$$ is an undirected graph with $$$n$$$ vertices, where an edge between vertices $$$u$$$ and $$$v$$$ exists if and only if the distance between vertices $$$u$$$ and $$$v$$$ in the given... | 1,800 | false | true | false | true | false | false | false | false | false | true | 1,446 |
1060D | You invited $$$n$$$ guests to dinner! You plan to arrange one or more circles of chairs. Each chair is going to be either occupied by one guest, or be empty. You can make any number of circles. Your guests happen to be a little bit shy, so the $$$i$$$-th guest wants to have a least $$$l_i$$$ free chairs to the left of ... | 1,900 | true | true | false | false | false | false | false | false | false | false | 5,413 |
175B | Vasya has been playing Plane of Tanks with his friends the whole year. Now it is time to divide the participants into several categories depending on their results. A player is given a non-negative integer number of points in each round of the Plane of Tanks. Vasya wrote results for each round of the last year. He has ... | 1,400 | false | false | true | false | false | false | false | false | false | false | 9,164 |
100I | Problem - 100I - Codeforces =============== xa0 , around the origin. What is the result of this rotation? Input A single integer _k_ (0u2009≤u2009_k_u2009<u2009360) is given in the first line. Two integer numbers _x_ and _y_ are given in the second line (u2009-u20091390u2009≤u2009_x_,u2009_y_u2009≤u20091390).... | 1,500 | true | false | false | false | false | false | false | false | false | false | 9,481 |
1473E | You are given a weighted undirected connected graph consisting of $$$n$$$ vertices and $$$m$$$ edges. It is guaranteed that there are no self-loops or multiple edges in the given graph. Let's define the weight of the path consisting of $$$k$$$ edges with indices $$$e_1, e_2, dots, e_k$$$ as $$$sumlimits_{i=1}^{k}{w_{e_... | 2,400 | false | false | false | false | false | false | false | false | false | true | 3,313 |
2009E | Problem - 2009E - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - ... | 1,400 | true | false | false | false | false | false | false | true | false | false | 196 |
331C1 | Yet another Armageddon is coming! This time the culprit is the Julya tribe calendar. The beavers in this tribe knew math very well. Smart Beaver, an archaeologist, got a sacred plate with a magic integer on it. The translation from Old Beaverish is as follows: "May the Great Beaver bless you! May your chacres open and ... | 1,100 | false | false | false | true | false | false | false | false | false | false | 8,518 |
301D | Problem - 301D - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 2,200 | false | false | false | false | true | false | false | false | false | false | 8,627 |
1729C | Polycarp was given a row of tiles. Each tile contains one lowercase letter of the Latin alphabet. The entire sequence of tiles forms the string $$$s$$$. In other words, you are given a string $$$s$$$ consisting of lowercase Latin letters. Initially, Polycarp is on the first tile of the row and wants to get to the last ... | 1,100 | false | false | false | false | false | true | false | false | false | false | 1,916 |
711A | ZS the Coder and Chris the Baboon are travelling to Udayland! To get there, they have to get on the special IOI bus. The IOI bus has _n_ rows of seats. There are 4 seats in each row, and the seats are separated into pairs by a walkway. When ZS and Chris came, some places in the bus was already occupied. ZS and Chris ar... | 800 | false | false | true | false | false | false | true | false | false | false | 6,976 |
523A | Polycarp is writing the prototype of a graphic editor. He has already made up his mind that the basic image transformations in his editor will be: rotate the image 90 degrees clockwise, flip the image horizontally (symmetry relative to the vertical line, that is, the right part of the image moves to the left, and vice ... | 1,200 | false | false | true | false | false | false | false | false | false | false | 7,746 |
1081G | Chouti thought about his very first days in competitive programming. When he had just learned to write merge sort, he thought that the merge sort is too slow, so he restricted the maximum depth of recursion and modified the merge sort to the following: Chouti found his idea dumb since obviously, this "merge sort" somet... | 3,200 | true | false | false | false | false | false | false | false | false | false | 5,317 |
894B | Problem - 894B - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,800 | true | false | false | false | false | true | false | false | false | false | 6,174 |
234E | In the autumn of this year, two Russian teams came into the group stage of the most prestigious football club competition in the world — the UEFA Champions League. Now, these teams have already started to play in the group stage and are fighting for advancing to the playoffs. In this problem we are interested in the dr... | 1,600 | false | false | true | false | false | false | false | false | false | false | 8,900 |
1731C | You are given an integer array $$$a_1, a_2, dots, a_n$$$ ($$$1 le a_i le n$$$). Find the number of subarrays of $$$a$$$ whose $$$operatorname{XOR}$$$ has an even number of divisors. In other words, find all pairs of indices $$$(i, j)$$$ ($$$i le j$$$) such that $$$a_i oplus a_{i + 1} oplus dots oplus a_j$$$ has an even... | 1,700 | true | false | false | false | false | false | true | false | false | false | 1,903 |
1612F | Monocarp plays a computer game. There are $$$n$$$ different sets of armor and $$$m$$$ different weapons in this game. If a character equips the $$$i$$$-th set of armor and wields the $$$j$$$-th weapon, their power is usually equal to $$$i + j$$$; but some combinations of armor and weapons synergize well. Formally, ther... | 2,800 | false | true | false | true | false | false | true | false | false | false | 2,578 |
935D | Ancient Egyptians are known to have used a large set of symbols to write on the walls of the temples. Fafa and Fifa went to one of the temples and found two non-empty words _S_1 and _S_2 of equal lengths on the wall of temple written one below the other. Since this temple is very ancient, some symbols from the words we... | 1,900 | true | false | false | false | false | false | false | false | false | false | 5,961 |
353E | You have a directed acyclic graph _G_, consisting of _n_ vertexes, numbered from 0 to _n_u2009-u20091. The graph contains _n_ edges numbered from 0 to _n_u2009-u20091. An edge with number _i_ connects vertexes _i_ and (_i_u2009+u20091)xa0_mod_xa0_n_, and it can be directed in either direction (from _i_ to (_i_u2009+u20... | 2,200 | false | true | false | true | false | false | false | false | false | false | 8,419 |
776A | Our beloved detective, Sherlock is currently trying to catch a serial killer who kills a person each day. Using his powers of deduction, he came to know that the killer has a strategy for selecting his next victim. The killer starts with two potential victims on his first day, selects one of these two, kills selected v... | 900 | false | false | true | false | false | false | true | false | false | false | 6,668 |
1701C | There are $$$n$$$ workers and $$$m$$$ tasks. The workers are numbered from $$$1$$$ to $$$n$$$. Each task $$$i$$$ has a value $$$a_i$$$xa0— the index of worker who is proficient in this task. Every task should have a worker assigned to it. If a worker is proficient in the task, they complete it in $$$1$$$ hour. Otherwis... | 1,400 | false | true | true | false | false | false | false | true | false | false | 2,074 |
572B | In this task you need to process a set of stock exchange orders and use them to create order book. An order is an instruction of some participant to buy or sell stocks on stock exchange. The order number _i_ has price _p__i_, direction _d__i_ — buy or sell, and integer _q__i_. This means that the participant is ready t... | 1,300 | false | true | true | false | true | false | false | false | true | false | 7,560 |
645G | After a drawn-out mooclear arms race, Farmer John and the Mischievous Mess Makers have finally agreed to establish peace. They plan to divide the territory of Bovinia with a line passing through at least two of the _n_ outposts scattered throughout the land. These outposts, remnants of the conflict, are located at the ... | 3,200 | false | false | false | false | false | false | false | true | false | false | 7,228 |
773D | In the country of Never, there are _n_ cities and a well-developed road system. There is exactly one bidirectional road between every pair of cities, thus, there are as many as roads! No two roads intersect, and no road passes through intermediate cities. The art of building tunnels and bridges has been mastered by Nev... | 2,700 | false | false | false | true | false | false | false | false | false | true | 6,684 |
1062F | There are $$$n$$$ cities in the kingdom $$$X$$$, numbered from $$$1$$$ through $$$n$$$. People travel between cities by some one-way roads. As a passenger, JATC finds it weird that from any city $$$u$$$, he can't start a trip in it and then return back to it using the roads of the kingdom. That is, the kingdom can be v... | 2,900 | false | false | false | false | false | false | false | false | false | true | 5,397 |
47E | Bertown is under siege! The attackers have blocked all the ways out and their cannon is bombarding the city. Fortunately, Berland intelligence managed to intercept the enemies' shooting plan. Let's introduce the Cartesian system of coordinates, the origin of which coincides with the cannon's position, the _Ox_ axis is ... | 2,200 | false | false | false | false | true | false | false | false | true | false | 9,738 |
1141D | There are $$$n$$$ left boots and $$$n$$$ right boots. Each boot has a color which is denoted as a lowercase Latin letter or a question mark ('?'). Thus, you are given two strings $$$l$$$ and $$$r$$$, both of length $$$n$$$. The character $$$l_i$$$ stands for the color of the $$$i$$$-th left boot and the character $$$r_... | 1,500 | false | true | true | false | false | false | false | false | false | false | 5,018 |
1842E | There are $$$n$$$ pairwise-distinct points and a line $$$x+y=k$$$ on a two-dimensional plane. The $$$i$$$-th point is at $$$(x_i,y_i)$$$. All points have non-negative coordinates and are strictly below the line. Alternatively, $$$0 leq x_i,y_i, x_i+y_i < k$$$. Tenzing wants to erase all the points. He can perform the f... | 2,300 | true | true | false | true | true | false | false | false | false | false | 1,235 |
1833A | Vlad decided to compose a melody on his guitar. Let's represent the melody as a sequence of notes corresponding to the characters 'a', 'b', 'c', 'd', 'e', 'f', and 'g'. However, Vlad is not very experienced in playing the guitar and can only record exactly two notes at a time. Vlad wants to obtain the melody $$$s$$$, a... | 800 | false | false | true | false | false | false | false | false | false | false | 1,291 |
140B | As meticulous Gerald sets the table, Alexander finished another post on Codeforces and begins to respond to New Year greetings from friends. Alexander has _n_ friends, and each of them sends to Alexander exactly one e-card. Let us number his friends by numbers from 1 to _n_ in the order in which they send the cards. Le... | 1,800 | false | true | true | false | false | false | true | false | false | false | 9,317 |
1809F | There are $$$n$$$ cities in Berland, arranged in a circle and numbered from $$$1$$$ to $$$n$$$ in clockwise order. You want to travel all over Berland, starting in some city, visiting all the other cities and returning to the starting city. Unfortunately, you can only drive along the Berland Ring Highway, which connect... | 2,500 | false | true | true | false | true | false | false | true | false | true | 1,415 |
778B | Bob recently read about bitwise operations used in computers: AND, OR and XOR. He have studied their properties and invented a new game. Initially, Bob chooses integer _m_, bit depth of the game, which means that all numbers in the game will consist of _m_ bits. Then he asks Peter to choose some _m_-bit number. After t... | 1,800 | false | false | true | false | false | false | true | false | false | false | 6,655 |
766A | While Mahmoud and Ehab were practicing for IOI, they found a problem which name was Longest common subsequence. They solved it, and then Ehab challenged Mahmoud with another problem. Given two strings _a_ and _b_, find the length of their longest uncommon subsequence, which is the longest string that is a subsequence o... | 1,000 | false | false | false | false | false | true | false | false | false | false | 6,723 |
1103D | Cardbluff is popular sport game in Telegram. Each Cardbluff player has ever dreamed about entrance in the professional layer. There are $$$n$$$ judges now in the layer and you are trying to pass the entrance exam. You have a number $$$k$$$ — your skill in Cardbluff. Each judge has a number $$$a_i$$$ — an indicator of u... | 3,100 | false | false | false | true | false | false | false | false | false | false | 5,184 |
1789B | Serval has a string $$$s$$$ that only consists of 0 and 1 of length $$$n$$$. The $$$i$$$-th character of $$$s$$$ is denoted as $$$s_i$$$, where $$$1leq ileq n$$$. Serval can perform the following operation called Inversion Magic on the string $$$s$$$: Choose an segment $$$[l, r]$$$ ($$$1leq lleq rleq n$$$). For $$$lle... | 800 | false | false | true | false | false | false | true | false | false | false | 1,547 |
958F2 | There is unrest in the Galactic Senate. Several thousand solar systems have declared their intentions to leave the Republic. Master Heidi needs to select the Jedi Knights who will go on peacekeeping missions throughout the galaxy. It is well-known that the success of any peacekeeping mission depends on the colors of th... | 1,800 | false | false | false | false | false | false | false | true | false | false | 5,879 |
187E | The story was not finished as PMP thought. God offered him one more chance to reincarnate and come back to life. But before he can come back, God told him that PMP should ask _n_ great men including prominent programmers about their life experiences. The men are standing on a straight line. They are numbered 1 through ... | 2,900 | false | true | false | false | true | false | false | false | false | false | 9,093 |
527D | The clique problem is one of the most well-known NP-complete problems. Under some simplification it can be formulated as follows. Consider an undirected graph _G_. It is required to find a subset of vertices _C_ of the maximum size such that any two of them are connected by an edge in graph _G_. Sounds simple, doesn't ... | 1,800 | false | true | true | true | true | false | false | false | true | false | 7,721 |
1068B | Problem - 1068B - Codeforces =============== xa0 ]( "A") $$$. Output Print one numberxa0— answer for the problem. Examples Input 1 Output 1 Input 2 Output 2 Note In the first example $$$ | 1,200 | true | false | false | false | false | false | false | false | false | false | 5,369 |
371B | Two little greedy bears have found two pieces of cheese in the forest of weight _a_ and _b_ grams, correspondingly. The bears are so greedy that they are ready to fight for the larger piece. That's where the fox comes in and starts the dialog: "Little bears, wait a little, I want to make your pieces equal" "Come off it... | 1,300 | true | false | false | false | false | false | false | false | false | false | 8,347 |
1761C | You are given a binary matrix $$$b$$$ (all elements of the matrix are $$$0$$$ or $$$1$$$) of $$$n$$$ rows and $$$n$$$ columns. You need to construct a $$$n$$$ sets $$$A_1, A_2, ldots, A_n$$$, for which the following conditions are satisfied: Each set is nonempty and consists of distinct integers between $$$1$$$ and $$... | 1,400 | false | true | false | false | false | true | false | false | false | true | 1,746 |
1671E | You are given a rooted tree of $$$2^n - 1$$$ vertices. Every vertex of this tree has either $$$0$$$ children, or $$$2$$$ children. All leaves of this tree have the same distance from the root, and for every non-leaf vertex, one of its children is the left one, and the other child is the right one. Formally, you are giv... | 2,100 | false | false | false | true | false | false | false | false | true | false | 2,247 |
1165F2 | The only difference between easy and hard versions is constraints. Ivan plays a computer game that contains some microtransactions to make characters look cooler. Since Ivan wants his character to be really cool, he wants to use some of these microtransactions — and he won't start playing until he gets all of them. Eac... | 2,000 | false | true | true | false | false | false | false | true | false | false | 4,890 |
1183B | There are $$$n$$$ products in the shop. The price of the $$$i$$$-th product is $$$a_i$$$. The owner of the shop wants to equalize the prices of all products. However, he wants to change prices smoothly. In fact, the owner of the shop can change the price of some product $$$i$$$ in such a way that the difference between... | 900 | true | false | false | false | false | false | false | false | false | false | 4,801 |
257D | Problem - 257D - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,900 | true | true | false | false | false | false | false | false | false | false | 8,804 |
913B | Problem - 913B - Codeforces =============== xa0 . Each of the next _n_u2009-u20091 lines contains one integer _p__i_ (1u2009≤u2009_i_u2009≤u2009_n_u2009-u20091)xa0— the index of the parent of the _i_u2009+u20091-th vertex (1u2009≤u2009_p__i_u2009≤u2009_i_). Vertex 1 is the root. It's guaranteed that the r... | 1,200 | false | false | true | false | false | false | false | false | false | false | 6,090 |
1198A | One common way of digitalizing sound is to record sound intensity at particular time moments. For each time moment intensity is recorded as a non-negative integer. Thus we can represent a sound file as an array of $$$n$$$ non-negative integers. If there are exactly $$$K$$$ distinct values in the array, then we need $$$... | 1,600 | false | false | false | false | false | false | false | false | true | false | 4,709 |
1917D | You are given a permutation $$$p_0, p_1, ldots, p_{n-1}$$$ of odd integers from $$$1$$$ to $$$2n-1$$$ and a permutation $$$q_0, q_1, ldots, q_{k-1}$$$ of integers from $$$0$$$ to $$$k-1$$$. An array $$$a_0, a_1, ldots, a_{nk-1}$$$ of length $$$nk$$$ is defined as follows: $$$a_{i cdot k+j}=p_i cdot 2^{q_j}$$$ for all $... | 2,300 | true | false | true | true | true | false | false | false | false | false | 791 |
1202B | Suppose you have a special $$$x$$$-$$$y$$$-counter. This counter can store some value as a decimal number; at first, the counter has value $$$0$$$. The counter performs the following algorithm: it prints its lowest digit and, after that, adds either $$$x$$$ or $$$y$$$ to its value. So all sequences this counter generat... | 1,700 | false | false | false | true | false | false | true | false | false | false | 4,688 |
733A | Problem - 733A - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,000 | false | false | true | false | false | false | false | false | false | false | 6,864 |
1705F | Mark is administering an online exam consisting of $$$n$$$ true-false questions. However, he has lost all answer keys. He needs a way to retrieve the answers before his client gets infuriated. Fortunately, he has access to the grading system. Thus, for each query, you can input the answers to all $$$n$$$ questions, and... | 2,900 | false | false | false | false | false | true | false | false | false | false | 2,041 |
1332E | Alice has got addicted to a game called Sirtet recently. In Sirtet, player is given an $$$n imes m$$$ grid. Initially $$$a_{i,j}$$$ cubes are stacked up in the cell $$$(i,j)$$$. Two cells are called adjacent if they share a side. Player can perform the following operations: stack up one cube in two adjacent cells; s... | 2,100 | true | false | false | false | false | true | false | false | false | false | 4,046 |
1343E | You are given an undirected unweighted graph consisting of $$$n$$$ vertices and $$$m$$$ edges (which represents the map of Bertown) and the array of prices $$$p$$$ of length $$$m$$$. It is guaranteed that there is a path between each pair of vertices (districts). Mike has planned a trip from the vertex (district) $$$a$... | 2,100 | false | true | false | false | false | false | true | false | true | true | 3,989 |
1644F | For an array of integers $$$a$$$, let's define $$$a$$$ as the number of elements in it. Let's denote two functions: $$$F(a, k)$$$ is a function that takes an array of integers $$$a$$$ and a positive integer $$$k$$$. The result of this function is the array containing $$$a$$$ first elements of the array that you get by... | 2,900 | true | false | false | false | false | false | false | false | false | false | 2,396 |
522C | Polycarp is flying in the airplane. Finally, it is his favorite time — the lunchtime. The BerAvia company stewardess is giving food consecutively to all the passengers from the 1-th one to the last one. Polycarp is sitting on seat _m_, that means, he will be the _m_-th person to get food. The flight menu has _k_ dishes... | 2,100 | false | true | false | false | false | false | false | false | false | false | 7,748 |
1849C | You are given a string $$$s$$$ consisting of $$$n$$$ characters 0 and/or 1. You make $$$m$$$ copies of this string, let the $$$i$$$-th copy be the string $$$t_i$$$. Then you perform exactly one operation on each of the copies: for the $$$i$$$-th copy, you sort its substring $$$[l_i; r_i]$$$ (the substring from the $$$l... | 1,600 | false | false | false | false | true | false | true | true | false | false | 1,186 |
245E | Problem - 245E - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 1,400 | false | true | true | false | false | false | false | false | false | false | 8,852 |
935F | Problem - 935F - Codeforces =============== xa0 ]( --- Finished → Virtual participation Virtual contest is a way to take part in past contest, as close as possible to participation on time. It is supported only ICPC mode for virtual contests. If you've seen these problems, a virtual contest is not for you - s... | 2,600 | false | true | false | false | true | false | false | false | false | false | 5,959 |
1494F | You are given an undirected connected graph consisting of $$$n$$$ vertices and $$$m$$$ edges. Your goal is to destroy all edges of the given graph. You may choose any vertex as the starting one and begin walking from it along the edges. When you walk along an edge, you destroy it. Obviously, you cannot walk along an ed... | 2,900 | false | false | true | false | false | true | true | false | false | true | 3,197 |
1618A | Polycarp had an array $$$a$$$ of $$$3$$$ positive integers. He wrote out the sums of all non-empty subsequences of this array, sorted them in non-decreasing order, and got an array $$$b$$$ of $$$7$$$ integers. For example, if $$$a = {1, 4, 3}$$$, then Polycarp wrote out $$$1$$$, $$$4$$$, $$$3$$$, $$$1 + 4 = 5$$$, $$$1 ... | 800 | true | false | false | false | false | false | false | false | true | false | 2,542 |
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