OJ题目:click here~~ 题目分析:输出第k个素数 贴这么简单的题目,目的不清纯 用筛法求素数的基本思想是:把从1開始的.某一范围内的正整数从小到大顺序排列, 1不是素数,首先把它筛掉.剩下的数中选择最小的数是素数,然后去掉它的倍数. 依次类推.直到筛子为空时结束. 如有: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1不是素数.去掉.剩下的数中2最小,是素数,去掉2的…

zk has n numbers a1,a2,...,ana1,a2,...,an. For each (i,j) satisfying 1≤i<j≤n, zk generates a new number (ai+aj)(ai+aj). These new numbers could make up a new sequence b1,b2,...,bn(n−1)/2b1,b2,...,bn(n−1)/2.  LsF wants to make some trouble. While zk i…

Problem Description Everybody knows any number can be combined by the prime number. Now, your task is telling me what position of the largest prime factor. The position of prime 2 is 1, prime 3 is 2, and prime 5 is 3, etc. Specially, LPF(1) = 0. Inpu…

http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=34870 求n内的素数个数. /* *********************************************** Author : zch Created Time :2015/5/19 8:46:16 File Name :a.cpp ************************************************ */ #include…

题意:一个4位的素数每次变动一个数位,中间过程也要上素数,问变成另一个的最小步数. 线性筛一遍以后bfs就好.我写的双向,其实没有必要. #include<cstdio> #include<iostream> #include<string> #include<cstring> #include<queue> #include<vector> #include<stack> #include<vector> #…

题意:题目比较容易混淆,要搞清楚一点,这里面所有的定义都是在4×k+1(k>=0)这个封闭的集合而言的,不要跟我们常用的自然数集混淆. 题目要求我们计算 H-semi-primes, H-semi-primes是 两个H-primes的乘积, H-primes的定义为:在这个集合中只能由1和它本来相乘得来,并且1不是 H-primes: 分析:这个题目我一开始是想打表记录一下的,但是没有筛法的效率,数据量过大,程序崩溃了(连超时的机会都不给我),看了多个别人的做法才知道,这个题目考查的是对于素数…

Description You've got an n × m matrix. The matrix consists of integers. In one move, you can apply a single transformation to the matrix: choose an arbitrary element of the matrix and increase it by 1. Each element can be increased an arbitrary numb…

题目描述: To facilitate the analysis of  a DNA sequence,  a DNA sequence is represented by a binary  number. The group of  DNA-1 has discovered a great new way .  There is a certain correlation between binary number and prime number. Instead of using the…

problem 3:Largest prime factor 题意:求600851475143的最大的质因数 代码如下: #ifndef PRO3_H_INCLUDED #define PRO3_H_INCLUDED #include "prime.h" namespace pro3{ long long solve(){ ;; ;i*i<=n;++i) ){ if(isPrime(n/i))return n/i; else if(isPrime(i))maxn=i; } >…

D. Dima and Lisa Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/584/problem/D Description Dima loves representing an odd number as the sum of multiple primes, and Lisa loves it when there are at most three primes. Help them…