
概率和数学期望
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主要关于概率、数学期望和其他数学专题
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常用求和公式和级数
数列级数 ∑k=1∞k=12n(n+1)∑k=1∞k=12n(n+1)\sum\limits_{k=1}^{\infty}k=\dfrac{1}{2}n(n+1) ∑k=1nk2=16n(n+1)(2n+1)∑k=1nk2=16n(n+1)(2n+1)\sum\limits_{k=1}^{n}k^2=\dfrac{1}{6}n(n+1)(2n+1) ∑k=1nk3=14n2(n+1)2∑k=...原创 2018-09-08 22:13:32 · 89299 阅读 · 1 评论 -
UVA - 10828-E - Back to Kernighan-Ritchie
Back to Kernighan-Ritchie题目大意:给出一个程序控制流程图,从每个结点出发到每个后继结点的概率都相等。当执行玩一个没有后继的结点后,整个程序终止,程序总是从编号为1的结点开始执行。对于若干查询结点,求出每个结点的期望执行次数。 解题思路:设结点ii的出度为did_i,对于一个拥有3个前驱结点a,b,ca,b,c的结点ii,可以列出方程xi=xa/da+xb/db+xc/dc原创 2017-08-14 12:49:21 · 324 阅读 · 0 评论 -
HDU6097-Mindis
MindisTime Limit: 6000/3000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 2678 Accepted Submission(s): 524 Special JudgeProblem Description The center coordin原创 2017-08-13 10:30:09 · 599 阅读 · 0 评论 -
2017"百度之星"程序设计大赛 - 初赛-今夕何夕
今夕何夕Accepts: 1345 Submissions: 5533 Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Problem Description今天是2017年8月6日,农历闰六月十五。小度独自凭栏,望着一轮圆月,发出了“今夕何夕,见此良人”的寂寞感慨。为了排遣郁结原创 2017-08-13 00:58:53 · 616 阅读 · 0 评论 -
2017"百度之星"程序设计大赛 - 初赛- 小C的倍数问题
小C的倍数问题Accepts: 1990 Submissions: 4931 Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others) Problem Description根据小学数学的知识,我们知道一个正整数x是3的倍数的条件是x每一位加起来的和是3的倍数。反之,如果一个数每一位加起来原创 2017-08-13 00:54:10 · 754 阅读 · 0 评论 -
COJ1979-古怪的行列式
1979: 古怪的行列式 Time Limit: 1 Sec Memory Limit: 128 Mb Submitted: 39 Solved: 13 Description这几天,子浩君潜心研究线性代数。 行列式的值定义如下: DET 其中,τ(j1j2…jn)为排列j1j2…jn的逆序数。子浩君很厉害的,但是头脑经常短路,所以他会按照行列式值的定义去计算原创 2017-08-13 00:44:06 · 682 阅读 · 0 评论 -
HDU6055-Regular polygon
Regular polygonTime Limit: 3000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 1105 Accepted Submission(s): 412Problem Description On a two-dimensional pla转载 2017-07-28 10:46:53 · 461 阅读 · 0 评论 -
HDU6045-Is Derek lying?
Is Derek lying?Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 412 Accepted Submission(s): 248Problem Description Derek and Alfia are good原创 2017-07-28 08:57:29 · 408 阅读 · 0 评论 -
HDU6106-Classes
ClassesTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 492 Accepted Submission(s): 307Problem Description The school set up three elective原创 2017-08-11 17:24:59 · 421 阅读 · 0 评论 -
异或方程组
#include<iostream>#include<cstdio>#include<vector>#include<algorithm>#include<cstring>using namespace std;const double eps=1e-8;const int MAXN=50;int a[MAXN][MAXN];//按下第i个格子是否会影响第j个格子int x[MA原创 2017-08-10 10:50:18 · 875 阅读 · 0 评论 -
COJ1911-Card Game
1911: Card GameSubmit Page Summary Time Limit: 3 Sec Memory Limit: 128 Mb Submitted: 51 Solved: 21 Description Alice and Bob now love to play a card game. Everyone is starting n ca原创 2017-08-03 09:40:31 · 424 阅读 · 0 评论 -
高斯消元
#include<iostream>#include<cstdio>#include<vector>#include<algorithm>#include<cstring>using namespace std;const double eps=1e-8;const int MAXN=1e3;typedef double Matrix[MAXN][MAXN];Matrix a;//原创 2017-08-09 18:09:12 · 291 阅读 · 0 评论 -
POJ2065-SETI
SETITime Limit: 1000MS Memory Limit: 30000K Total Submissions: 2144 Accepted: 1318 DescriptionFor some years, quite a lot of work has been put into listening to electromagnetic radio signals原创 2017-08-07 10:02:53 · 447 阅读 · 0 评论 -
AtCoder Regular Contest 080-C - 4-adjacent
C - 4-adjacent Time limit : 2sec / Memory limit : 256MBScore : 400 pointsProblem Statement We have a sequence of length N, a=(a1,a2,…,aN). Each ai is a positive integer.Snuke’s objective is to permut原创 2017-08-07 10:57:02 · 937 阅读 · 0 评论 -
佩尔方程
暴力法求特解//佩尔方程-暴力法求特解//x^2-dy^2=1//x_n=x_{n-1}x_1+dy_{n-1}y_1//y_n=x_{n-1}y_1+y_{n-1}x_1void calc(int &amp;amp;amp;x,int &amp;amp;amp;y,int d){ x=y=0; do{ y++; x=(int)sqrt(d*y*y+1); ...原创 2018-08-07 18:44:19 · 723 阅读 · 0 评论 -
多项式与快速傅里叶变换
多项式A(x)=∑j=0n−1ajxj" role="presentation" style="position: relative;">A(x)=∑j=0n−1ajxjA(x)=∑j=0n−1ajxjA(x)=\sum\limits_{j=0}^{n-1}a_jx^j B(x)=∑j=0n−1bjxj" role="presentat原创 2018-01-29 15:59:59 · 651 阅读 · 0 评论 -
Tenka1 Programmer Contest-D - IntegerotS
Time limit : 2sec / Memory limit : 256MBScore : 500 pointsProblem Statement Seisu-ya, a store specializing in non-negative integers, sells N non-negative integers. The i-th integer is Ai and has a uti原创 2017-10-01 12:00:26 · 310 阅读 · 0 评论 -
CF838A-Binary Blocks
A. Binary Blockstime limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard outputYou are given an image, that can be represented with a 2-d n by m gri原创 2017-08-15 10:06:44 · 1896 阅读 · 0 评论 -
CodeForces 621C
C. Wet Shark and Flowerstime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputThere are n sharks who grow flowers for Wet原创 2016-08-22 15:24:38 · 421 阅读 · 0 评论 -
HDU1597
find the nth digitTime Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 11884 Accepted Submission(s): 3572Problem Description假设:S1原创 2016-08-22 11:00:35 · 419 阅读 · 0 评论 -
POJ3372
Candy DistributionTime Limit: 1000MSMemory Limit: 65536KTotal Submissions: 6009Accepted: 3339DescriptionN children standing in circle who are numbered 1 throu原创 2016-08-21 16:07:29 · 420 阅读 · 0 评论 -
CodeForces - 1A
A. Theatre Squaretime limit per test1 secondmemory limit per test256 megabytesinputstandard inputoutputstandard outputTheatre Square in the capital city of Berland has a原创 2016-07-22 19:58:52 · 500 阅读 · 0 评论 -
HDU1061
Rightmost DigitTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/32768 K (Java/Others)Total Submission(s): 47526 Accepted Submission(s): 17954Problem DescriptionGiven a po原创 2016-07-22 20:09:09 · 524 阅读 · 0 评论 -
POJ1995
Raising Modulo NumbersTime Limit: 1000MSMemory Limit: 30000KTotal Submissions: 6486Accepted: 3827DescriptionPeople are different. Some secretly read magazines f原创 2016-07-22 20:27:06 · 588 阅读 · 0 评论 -
2016CCPC东北地区大学生程序设计竞赛-Mr. Frog’s Problem
Mr. Frog’s ProblemTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 0 Accepted Submission(s): 0Problem DescriptionOne day, yo原创 2016-10-06 15:05:18 · 1133 阅读 · 0 评论 -
HDU6063-RXD and math
RXD and mathTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 524288/524288 K (Java/Others) Total Submission(s): 448 Accepted Submission(s): 230Problem Description RXD is a good mathematicia原创 2017-08-02 10:03:48 · 638 阅读 · 0 评论 -
CF834B-The Festive Evening
B. The Festive Eveningtime limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard outputIt’s the end of July – the time when a festive evening is held at Jelly原创 2017-07-31 09:54:35 · 820 阅读 · 0 评论 -
CF833A-The Meaningless Game
A. The Meaningless Gametime limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard output Slastyona and her loyal dog Pushok are playing a meaningless game t原创 2017-07-31 09:42:45 · 2115 阅读 · 0 评论 -
CF818A-Diplomas and Certificates
A. Diplomas and Certificatestime limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard output There are n students who have taken part in an olympiad. Now it’原创 2017-06-30 01:58:52 · 584 阅读 · 0 评论 -
COJ1957-Apache还想再活五百年
Apache还想再活五百年Description Apache总是觉得人生短暂,不能够尽欢。所以他还想再活五百年,于是Apache变跋山涉水来到传说中的蓬莱仙岛向各位长者询问长生的秘诀。长者毕竟是长者,怎么可能让一个年轻人如此容易的得到如此秘诀呢。长者给Apache设置了九九八十一道题目,通关后便可取得秘诀,再活五百年。长者给出的第一道题目如下: 蓬莱仙岛上曾经住着很多长者,我现在给出若干个长者的原创 2017-06-17 21:49:19 · 852 阅读 · 0 评论 -
UVA-10590 正整数拆分
Boxes of Chocolates AgainLittle Pippy has got again a big bunch of boxes of chocolates on her 7-th birthday. Her parents are anxious about the health of her teeth, so they have allowed her to take onl原创 2017-05-21 11:13:28 · 741 阅读 · 0 评论 -
《具体数学》学习笔记-递归问题
1、平面上n条直线所界定的区域的最大个数LnL_n 是多少? L0=1L_0=1 Ln=Ln−1+n,n>0L_n=L_{n-1}+n, n>0 Ln=n(n+1)2+1L_n=\frac{n(n+1)}{2}+1 变式:用折线代替直线,如果放置得当,对每条折线我们仅仅损失两个区域。 Zn=L2n−2n=2n2−n+1,n≥0Z_n=L_{2n}-2n=2n^2-n+1,n\ge 0 2原创 2017-05-18 17:55:29 · 999 阅读 · 0 评论 -
中南大学第十一届大学生程序设计竞赛-COJ1897-The price table of the snack store
1897: The price table of the snack storeSubmit Page Summary Time Limit: 1 Sec Memory Limit: 128 Mb Submitted: 28 Solved: 7 Description CSUACM team is a group of people who like eat原创 2017-04-26 09:21:37 · 1032 阅读 · 0 评论 -
中南大学第十一届大学生程序设计竞赛-COJ1895-Apache is late again
1895: Apache is late againSubmit Page Summary Time Limit: 1 Sec Memory Limit: 128 Mb Submitted: 7 Solved: 3 Description Apache is a student of CSU. There is a math class every Sund原创 2017-04-24 22:31:49 · 1001 阅读 · 0 评论 -
COJ-1008-Horcrux
1008: HorcruxSubmit Page Summary Time Limit: 1 Sec Memory Limit: 128 Mb Submitted: 610 Solved: 165 Description A Horcrux is an object in which a Dark wizard or witch has hidden a f原创 2017-05-06 11:54:58 · 760 阅读 · 0 评论 -
2017湖南多校第二场-20170312
1836: Square Submit Status Time Limit: 1 Sec Memory Limit: 128 Mb Submitted: 33 Solved: 14 Description It was the first time that our government organized the 2015 ACM PCPC (Pape原创 2017-03-15 15:00:24 · 537 阅读 · 0 评论 -
2017湖南多校第一场-Generations of Tribbles
G(1006): Generations of Tribbles Submit Page Summary Time Limit: 5 Sec Memory Limit: 128 Mb Submitted: 25 Solved: 23 Description Tribbles are the cute, fuzzy, cuddly animals原创 2017-03-22 13:34:13 · 545 阅读 · 0 评论 -
2017湖南多校第一场-F(1005): Federation Favorites
F(1005): Federation Favorites Submit Page Summary Time Limit: 5 Sec Memory Limit: 128 Mb Submitted: 46 Solved: 23 Description En route to Rigel 7, Chief Engineer Geordi Laforge a原创 2017-03-22 13:14:23 · 581 阅读 · 0 评论 -
2016CCPC东北地区大学生程序设计竞赛-Minimum’s Revenge
Minimum’s RevengeTime Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 0 Accepted Submission(s): 0Problem DescriptionThere is a g原创 2016-10-06 15:15:09 · 970 阅读 · 0 评论 -
CF818B-Permutation Game
B. Permutation Gametime limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard output n children are standing in a circle and playing a game. Children’s number原创 2017-06-30 02:03:59 · 1138 阅读 · 0 评论