Prime Numbers in a Grid素数网格

/* * hdu How many prime numbers * date 2014/5/13 * state AC */ #include <iostream> #include <cmath> #include <cstdio> using namespace std; bool isPrime(int x) { int sqr=sqrt(x*1.0); for(int i=2;i<=sqr;i++) { if(x%i==0)return false; }

How many prime numbers Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 12955    Accepted Submission(s): 4490 Problem Description Give you a lot of positive integers, just to find out how many pr

Sum of Consecutive Prime Numbers Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 19350 Accepted: 10619 Description Some positive integers can be represented by a sum of one or more consecutive prime numbers. How many such representations d

题意:输入两个正整数L.U(L<=U<1012),统计区间[L,U]的整数中有多少个数满足:它本身不是素数,但只有一个素因子. 分析: 1.满足条件的数是素数的倍数. 2.枚举所有的素数,以及其倍数,将满足条件且小于等于n的个数计算出来,solve(u) - solve(l - 1)即可. #pragma comment(linker, "/STACK:102400000, 102400000") #include<cstdio> #include<cst

题目大意:判断一个数是否是两个素数的乘积,如果是,输出Yes,否则No. 分析:先打表求出来一部分素因子,用素数对素数判定还是比较快的. 代码如下: =============================================================================================================================== #include<stdio.h> #include<algorithm> #i

题目链接: huangjing 思路:每一个数都可以表示成若干个素数的乘积,那么可以对N从2一直枚举到sqrt(N),然后对每个数都能除到不能取余为止,那么后面的合数就不会除了,所以最后得到的数就是最大的质因子,然后直接N/最大的质因子,还有就是N=1的时候没有存在的数  . 题目: Alexandra and Prime Numbers Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Oth

Sieve of Eratosthenes (素数筛选算法) Given a number n, print all primes smaller than or equal to n. It is also given that n is a small number. For example, if n is 10, the output should be “2, 3, 5, 7″. If n is 20, the output should be “2, 3, 5, 7, 11, 13,

题目就是给出一组数,让我们测试其中有多少个是素数. 求素数有测试sqrt(n)个数的方法,有筛子方法,不过对于本题这样的题目来说就都不是高效的. 本题使用Miller Rabin素数测试法,效率奇高,对于不是极其大的整数测试都几乎是常数时间.令人神往的算法啊. 网上有个程序,好像是什么吉林的模板程序,不过我一直没看懂他是什么思路写的,是个AC的程序,不过却是错误的,呵呵,因为程序一直把9当做素数. 于是上网查找了其中原理,自己写了个程序,效率和他的差不多一样,通过时间基本无差别,不过我的思路是按

Problem AAlmost Prime NumbersTime Limit: 1 second Almost prime numbers are the non-prime numbers which are divisible by only a single prime number. In this problem your job is to write a program which finds out the number of almost prime numbers with