While preparing this problem set the jury has run into the following problem: it was necessary to send by e-mail the texts of the problems. As it is well known, e-mail is not reliable, messages are sent not enciphered, there is a danger that someone…
暴力搞肯定不行,因此我们从小到大枚举素数,用n去试除,每次除尽,如果已经超过20,肯定是no.如果当前枚举到的素数的(20-已经找到的质因子个数)次方>剩下的n,肯定也是no.再加一个关键的优化,如果剩下的次数是1了,就直接判定剩下的n是否是素数.这样可以保证次方>=2,将我们需要枚举的素数限制在200w以内,就可做了.线性筛在这题虽然不必要,但是可以当个板子存下来. The hacker Michael develops breakthrough password manager, whic…
.net web程序使用rsa算法进行加解密时,程序报告“System.Security.Cryptography.CryptographicException: 拒绝访问”错.按网上搜的解决方法做了各种权限配置,然并卵.试了两天终于解决,现记录如下: C:\Documents and Settings\All Users\Application Data 添加项目应用程序池对应启动帐号(或iis_wpg组) 读取,读取并运行,列出文件夹目录权限. C:\Documents and Settin…
[POJ2109]Power of Cryptography 试题描述 Current work in cryptography involves (among other things) large prime numbers and computing powers of numbers among these primes. Work in this area has resulted in the practical use of results from number theory a…
2071. Juice Cocktails Time limit: 1.0 secondMemory limit: 64 MB Once n Denchiks come to the bar and each orders a juice cocktail. It could be from 1 to 3 different juices in each cocktail. There are three juices in the bar: apple, banana and pineappl…
2073. Log Files Time limit: 1.0 secondMemory limit: 64 MB Nikolay has decided to become the best programmer in the world! Now he regularly takes part in various programming contests, attentively listens to problems analysis and upsolves problems. But…
2070. Interesting Numbers Time limit: 2.0 secondMemory limit: 64 MB Nikolay and Asya investigate integers together in their spare time. Nikolay thinks an integer is interesting if it is a prime number. However, Asya thinks an integer is interesting i…
2069. Hard Rock Time limit: 1.0 secondMemory limit: 64 MB Ilya is a frontman of the most famous rock band on Earth. Band decided to make the most awesome music video ever for their new single. In that music video Ilya will go through Manhattan standi…
2068. Game of Nuts Time limit: 1.0 secondMemory limit: 64 MB The war for Westeros is still in process, manpower and supplies are coming to an end and the winter is as near as never before. The game of thrones is unpredictable so Daenerys and Stannis…
2067. Friends and Berries Time limit: 2.0 secondMemory limit: 64 MB There is a group of n children. According to a proverb, every man to his own taste. So the children value strawberries and raspberries differently. Let’s say that i-th child rates hi…
2066. Simple Expression Time limit: 1.0 secondMemory limit: 64 MB You probably know that Alex is a very serious mathematician and he likes to solve serious problems. This is another problem from Alex. You are given three nonnegative integers a, b, c.…
2065. Different Sums Time limit: 1.0 secondMemory limit: 64 MB Alex is a very serious mathematician and he likes to solve serious problems. For example, this problem. You are to construct an array of n integers in which the amount of different intege…
2064. Caterpillars Time limit: 3.0 secondMemory limit: 64 MB Young gardener didn’t visit his garden for a long time, and now it’s not very pleasant there: ncaterpillars have appeared on the ground. Kirill decided to use this opportunity to have some…
2063. Black and White Time limit: 1.0 secondMemory limit: 64 MB Let’s play a game. You are given a row of n balls, each ball is either black or white. Their positions in a row are numbered from 1 to n. You know the total number of balls n, but have n…
2062. Ambitious Experiment Time limit: 3.0 secondMemory limit: 128 MB During several decades, scientists from planet Nibiru are working to create an engine that would allow spacecrafts to fall into hyperspace and move there with superluminal velocity…
1255. Graveyard of the Cosa Nostra Time limit: 1.0 secondMemory limit: 64 MB There is a custom among the Ural Mafiosi — a big Mafioso’s coffin is to be carried by all his subordinates. The length of the coffin (in meters) equals to the number of the…
1252. Sorting the Tombstones Time limit: 1.0 secondMemory limit: 64 MB There is time to throw stones and there is time to sort stones… An old desolate cemetery is a long dismal row of nameless tombstones There are N tombstones of various shapes. The…
1251. Cemetery Manager Time limit: 1.0 secondMemory limit: 64 MB There is a tradition at the USU championships to call the most hard-to-solve problems coffins. But to distribute coffins is also a very difficult problem. Consider a cemetery with place…
1250. Sea Burial Time limit: 1.0 secondMemory limit: 64 MB There is Archipelago in the middle of a shoreless ocean. An ancient tribe of cannibals lives there. Shamans of this race have been communicating with gods and admonishing people for ages. The…
1249. Ancient Necropolis Time limit: 5.0 secondMemory limit: 4 MB Aerophotography data provide a bitmap picture of a hard-to-reach region. According to the suggestions of scientists, this region is a cemetery of an extinct civilization. Indeed, the p…
1075. Thread in a Space Time limit: 1.0 secondMemory limit: 64 MB There are three points in a 3-dimensional space: A, B and C. All the coordinates of the points are integer numbers with absolute values not greater than 1000. A solid ball with a cente…
1073. Square Country Time limit: 1.0 secondMemory limit: 64 MB There live square people in a square country. Everything in this country is square also. Thus, the Square Parliament has passed a law about a land. According to the law each citizen of th…
1072. Routing Time limit: 1.0 secondMemory limit: 64 MB There is a TCP/IP net of several computers. It means that: Each computer has one or more net interfaces. Each interface is identified by its IP-address and a subnet mask — these are two four-byt…
