A. Primes or Palindromes?Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://poj.org/problem?id=3261 Description Rikhail Mubinchik believes that the current definition of prime numbers is obsolete as they are too complex and unpredictable. A palindro…

C. Primes or Palindromes? time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard output Rikhail Mubinchik believes that the current definition of prime numbers is obsolete as they are too complex and un…

题目:Click here 题意:π(n)表示不大于n的素数个数,rub(n)表示不大于n的回文数个数,求最大n,满足π(n) ≤ A·rub(n).A=p/q; 分析:由于这个题A是给定范围的,所以可以先暴力求下最大的n满足上式,可以想象下随着n的增大A也在增大(总体正相关,并不是严格递增的),所以二分查找时不行的,所以对给定的A,n是一定存在的.这个题的关键就是快速得到素数表最好在O(n)的时间以内.(杭电15多校的一个题也用到了这个算法点这里查看) #include <bits/stdc+…

这道题居然是一个大暴力... 题意: π(n):小于等于n的数中素数的个数 rub(n) :小于等于n的数中属于回文数的个数 然后给你两个数p,q,当中A=p/q. 然后要你找到对于给定的A.找到使得π(n) ≤ A·rub(n) 最大的n. (A<=42) 思路: 首先我们能够暴力算出当n为大概150万左右的时候,π(n)大概是 rub(n) 的42倍. 所以我们仅仅须要for到150万左右就好,由于对于后面的式子.肯定能在150万的范围内找到一个n使得这个式子成立的. 并且.我们可以得出由于…

Codeforces Round #297 (Div. 2)D. Arthur and Walls Time Limit: 2 Sec  Memory Limit: 512 MBSubmit: xxx  Solved: 2xx 题目连接 http://codeforces.com/contest/525/problem/D Description Finally it is a day when Arthur has enough money for buying an apartment. H…

比赛链接:http://codeforces.com/contest/569 A. Music time limit per test:2 seconds memory limit per test:256 megabytes Little Lesha loves listening to music via his smartphone. But the smartphone doesn't have much memory, so Lesha listens to his favorite…

题意:求使pi(n)*q<=rub(n)*p成立的最大的n. 先收集所有的质数和回文数.质数好搜集.回文数奇回文就0-9的数字,然后在头尾添加一个数.在x前后加a,就是x*10+a+a*pow(10,2).偶回文同理.然后不能二分,因为比值不是单调的. 乱码: #pragma comment(linker,"/STACK:1024000000,1024000000") #include<iostream> #include<cstdio> #include…

链接: https://codeforces.com/contest/1228/problem/C 题意: Let's introduce some definitions that will be needed later. Let prime(x) be the set of prime divisors of x. For example, prime(140)={2,5,7}, prime(169)={13}. Let g(x,p) be the maximum possible int…

这次可以说是最糟糕的一次比赛了吧, 心没有静下来好好的去思考, 导致没有做好能做的题. Problem_A: 题意: 你要听一首时长为T秒的歌曲, 你点击播放时会立刻下载好S秒, 当你听到没有加载到的地方时, 就会重头听, 直到可以听完整首歌, 由于网络堵塞, 你在q秒内只有q-1秒用于下载, 问需要重新多少次, 第一次点击播放也算. 思路: 由题意可知, 下载速度为(q - 1) / q , 假设t秒后听歌的进度和下载的进度一样, 即听到没有下载的地方or已经下载完. 可以得到方程: (q -…

题目:Click here 题意:给你n,然后n个数,n个数中可能重复,可能不是1到n中的数.然后你用最少的改变数,让这个序列包含1到n所有数,并输出最后的序列. 分析:贪心. #include <bits/stdc++.h> using namespace std; ; int n; int a[M]; // 给定序列 int mark[M]; // mark[i] 表示i在给定序列中的出现次数 int notap[M]; // 给的序列中没有出现的元素 bool firstout; voi…

题目:Click here 题意:(据说这个题的题意坑了不少人啊~~~)题目一共给了3个数---- T 表示歌曲的长度(s).S 表示下载了歌曲的S后开始第一次播放(也就是说S秒的歌曲是事先下载好的).q 表示下载速度(每秒下载歌曲(q-1)/q秒).问题就是播放的速度比下载的速度快,每当播放到没下载的位置,就会重新从头播放,输出的就是从头播放的次数(包括第一次). 分析:高中物理追击问题,模拟下好了. #include <bits/stdc++.h> using namespace std;…

B. Inventory time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Companies always have a lot of equipment, furniture and other things. All of them should be tracked. To do this, there is an inv…

A. Music time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Little Lesha loves listening to music via his smartphone. But the smartphone doesn't have much memory, so Lesha listens to his favo…

B. Inventory time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Companies always have a lot of equipment, furniture and other things. All of them should be tracked. To do this, there is an inv…

A. Music time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Little Lesha loves listening to music via his smartphone. But the smartphone doesn't have much memory, so Lesha listens to his favo…

 B. Mike and Fun Time Limit: 20 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/548/problem/A Description Mike and some bears are playing a game just for fun. Mike is the judge. All bears except Mike are standing in an n × m grid, there'…

C. Divisibility by Eight Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/550/problem/C Description You are given a non-negative integer n, its decimal representation consists of at most 100 digits and doesn't contain leadin…

A. Borya and Hanabi Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/442/problem/A Description Have you ever played Hanabi? If not, then you've got to try it out! This problem deals with a simplified version of the game. Ove…

B. Equivalent Strings Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/559/problem/B Description Today on a lecture about strings Gerald learned a new definition of string equivalency. Two strings a and b of equal length are…

C. Amr and Chemistry Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/558/problem/C Description Amr loves Chemistry, and specially doing experiments. He is preparing for a new interesting experiment. Amr has n different type…

A. Vanya and Table Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/552/problem/A Description Vanya has a table consisting of 100 rows, each row contains 100 cells. The rows are numbered by integers from 1 to 100 from bottom…

A. Fight the Monster Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/487/problem/A Description A monster is attacking the Cyberland! Master Yang, a braver, is going to beat the monster. Yang and the monster each have 3 attr…

C. Edo and Magnets Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/594/problem/C Description Edo has got a collection of n refrigerator magnets! He decided to buy a refrigerator and hang the magnets on the door. The shop ca…

A. Vitaly and Night Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/595/problem/A Description One day Vitaly was going home late at night and wondering: how many people aren't sleeping at that moment? To estimate, Vitaly de…

C. Letter Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/180/problem/C Description Patrick has just finished writing a message to his sweetheart Stacey when he noticed that the message didn't look fancy. Patrick was nervou…

C. Gennady the Dentist Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/586/problem/C Description Gennady is one of the best child dentists in Berland. Today n children got an appointment with him, they lined up in front of h…

http://codeforces.com/contest/465/problem/C 给定n和m,以及一个字符串s,s不存在长度大于2的回文子串,如今要求输出一个字典比s大的字符串,且串中字母在一定范围内,而且说相同不存在长度大于2的回文子串. 直接去递归构造就可以.从最后一位開始.每次仅仅要推断是否子串中含有回文串,事实上细致想想仅仅要考虑是否存在一个字符和前两个字符中的一个同样就可以.不卡时限,裸的推断都能过 #include <cstdio> #include <cstdlib&…

A. Saitama Destroys Hotel time limit per test:1 second memory limit per test:256 megabytes input:standard input output:standard output Saitama accidentally destroyed a hotel again. To repay the hotel company, Genos has volunteered to operate an eleva…

A. Vladik and Courtesy time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output At regular competition Vladik and Valera won a and b candies respectively. Vladik offered 1 his candy to Valera. Afte…

 A. Mike and Fax Time Limit: 20 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/548/problem/A Description While Mike was walking in the subway, all the stuff in his back-bag dropped on the ground. There were several fax messages among th…