龙崎的专栏

题目描述：判断一个整数是否是回文数。回文数是指正序（从左向右）和倒序（从右向左）读都是一样的整数。示例 1:输入: 121输出: true示例 2:输入: -121输出: false解释: 从左向右读, 为 -121 。 从右向左读, 为 121- 。因此它不是一个回文数。示例 3:输入: 10输出: false解释: 从右向左读, 为 01 。因此...

题意：对于1~n的排列，至少交换k次才能变成1,2,3,...,n的有多少个思路：假设每一个排列是一个置换，这个置换里有x个循环，那么这个置换想变成1,2,3,...,n至少交换n-x次，所以题意也就是有多少个排列，里面的循环这个可以有dp来做，dp[i][j]表示至少交换j次，变成1,2,...,idp[i][j]=dp[i-1][j]+dp[i-1][j-1]*(i-1)dp[

序列变换  Accepts: 695  Submissions: 3322 Time Limit: 2000/1000 MS (Java/Others)  Memory Limit: 32768/32768 K (Java/Others)Problem Description我们有一个数列A1,A2...An，你现在要求修改数量最少的

C. Mike and FrogMike has a frog and a flower. His frog is named Xaniar and his flower is named Abol. Initially(at time0), height of Xaniar is h1 and height of Abol ish2. Each second, Mike

C. Mike and Foamtime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputMike is a bartender at Rico's bar. At Rico's, they p

CodeTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 319    Accepted Submission(s): 128Problem DescriptionWLD likes playing with code

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Tom and matrixTime Limit: 3000/1500 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 189    Accepted Submission(s): 57Problem DescriptionTom was on the way

Tom and permutationTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 201    Accepted Submission(s): 87Problem DescriptionTom has learn

zhx's contestTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 562    Accepted Submission(s): 177Problem DescriptionAs one of the most

Colorful ToyTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others)Total Submission(s): 304    Accepted Submission(s): 100Problem DescriptionA toy is made up

DoomTime Limit: 12000/6000 MS (Java/Others)    Memory Limit: 524288/524288 K (Java/Others)Total Submission(s): 426    Accepted Submission(s): 96Problem DescriptionTHE END IS COMINGGGGGG!

原来还不知道中国剩余定理能干什么用，先上几篇中国剩余定理的介绍下面内容转自：http://wenku.baidu.com/link?url=g1Hiu6UtSoOR6Y3tiHpn5M3_HPnuoTN_xpm1GPFHAkZB-nW0m61vunMmNIqxacAke3jPmMvE_M4gWGd25D0C1ZthZTuzx-u1DHSbunP8qrS“中国剩余定理”算理及其应

Virtual ParticipationProblem DescriptionAs we know, Rikka is poor at math. Yuta is worrying about this situation, so he asks rikka to have some practice on codeforces. Then she opens the problem B:Give

MagicianProblem DescriptionFantasy magicians usually gain their ability through one of three usual methods: possessing it as an innate talent, gaining it through study and practice, or receiving it fro

The Boss on MarsOn Mars, there is a huge company called ACM (A huge Company on Mars), and it’s owned by a younger boss.Due to no moons around Mars, the employees can only get the salaries per-year. The

A. Lengthening SticksYou are given three sticks with positive integer lengths of a, b, and c centimeters. You can increase length of some of them by some positive integer number of centimeters (differe

Y sequenceProblem DescriptionYellowstar likes integers so much that he listed all positive integers in ascending order,but he hates those numbers which can be written as a^b (a, b are positive integers

D-City Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65535/65535 K (Java/Others) Total Submission(s): 2437 Accepted Submission(s): 859Problem Description Luxer is a really bad guy. He d

E. Gerald and Giant ChessGiant chess is quite common in Geraldion. We will not delve into the rules of the game, we’ll just say that the game takes place on an h × w field, and it is painted in two col

OO’s SequenceProblem Description OO has got a array A of size n ,defined a function f(l,r) represent the number of i (l<=i<=r) , that there’s no j(l<=j<=r,j<>i) satisfy ai mod aj=0,now OO want to know

大搬家Accepts: 1516Submissions: 6288Time Limit: 2000/1000 MS (Java/Others)Memory Limit: 65536/65536 K (Java/Others)Problem Description近期B厂组织了一次大搬家，所有人都要按照指示换到指定的座位上。指示的内容是坐在位置i上

pog loves szh IAccepts: 497Submissions: 822Time Limit: 2000/1000 MS (Java/Others)Memory Limit: 65536/65536 K (Java/Others)问题描述pog拥有很多字符串，它喜欢将两个长度相等字符串交错拼在一起，如abcd与efgh，那么交错拼在一起就成

Misaki's Kiss againTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 820    Accepted Submission(s): 205Problem DescriptionAfter the Fe

官方题解：令(x, y)表示高分为x，低分为y的状态（x >= y），E(x, y)表示从(x, y)到达(1000, ?)的比赛场数期望。容易得到E(x, y) = P * E(x1, y1) + (1 - P) * E(x2, y2) + 1，其中，(x1, y1)表示rating上升后的状态，（x2, y2）表示rating下降后的状态。每50分一个状态，共有210个状态（21*20/2

刚开始出的两个题还挺快的，结果后来就掉的

Language:DefaultCensored!Time Limit: 5000MS Memory Limit: 10000KTotal Submissions: 8102 Accepted: 2191DescriptionThe alphabet of Freeland consists of exac

题意 ：在平面坐标系的第一象限上，从原点出发，到 (n, 0) 的种类。思路 ： 卡塔兰数。c[n] = 2n! / ((n+1)! n!) =  c(2n, n) / (n + 1)       因为始点与终点是水平的。 所以向上多少，向下就要多少，其余的都是水平前景的。    假设 上升了 k 次  那就必须下降 k 次   所以 a[k] = c(n, 2k) * c(2

Online JudgeOnline ExerciseOnline TeachingOnline ContestsExercise AuthorF.A.QHand In HandOnline AcmersForum | DiscussStatistical ChartsProblem ArchiveRealtime Judge Statu

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25431300input3 11000000000 1000000000 1000000000? 1 3 0output999999986题意：

I - Dividing StonesTime Limit:7000MS     Memory Limit:0KB     64bit IO Format:%lld & %lluSubmit Status Practice SPOJ AMR10IDescriptionThere are N stones, which can be divided int

反素数：对于任何正整数x,其约数的个数记做g(x).例如g(1)=1,g(6)=4.如果某个正整数x满足：对于任意i(0

在数论中的积性函数：对于正整数n的一个算术函数 f(n)，若f(1)=1，且当a,b互质时f(ab)=f(a)f(b)，在数论上就称它为积性函数。若对于某积性函数 f(n) ，就算a, b不互质，也有f(ab)=f(a)f(b)，则称它为完全积性的。φ(n) －欧拉函数，计算与n互质的正整数之数目μ(n) －莫比乌斯函数，关于非平方数的质因子数目

【关于 A^x = A^(x % Phi(C) + Phi(C)) (mod C) 的若干证明】【指数循环节】以下内容全部原创，转载请注明作者 : AekdyCoin 以及本文地址曾经看过如下一个公式:以上的公式如果第一次见到，难免有不少疑惑:为什么可以这么写?限制条件为什么是x >= Phi(C),这个公式为什么正确?今天突发奇想,在纸上YY以后得

E. DZY Loves Fibonacci NumbersIn mathematical terms, the sequence Fn of Fibonacci numbers is defined by the recurrence relationF1 = 1; F2 = 1; Fn = Fn - 1 + Fn - 2 (n > 2).DZY loves Fibo

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C. Gargari and Bishopstime limit per test3 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputGargari is jealous that his friend Caisa won t

Cracking RSATime Limit:250MS Memory Limit:65536KB 64bit IO Format:%I64d & %I64uSubmitStatusDescription200. Cracking RSA time limit per test: 0.25 sec. memor

Language:DefaultWidget FactoryTime Limit: 7000MS Memory Limit: 65536KTotal Submissions: 4689 Accepted: 1595DescriptionThe widget factory produces several