题目链接 题意:问从A到B中与N互素的个数. 题解: 利用容斥原理:先求出与n互为素数的个数. 可以先将 n 进行素因子分解,然后用区间 x 除以 素因子,就得到了与 n 的 约数是那个素因子的个数,然后每次这样求一遍,但是发现有重 复的:举个例子 [1,10] 区间中与 6 互素的个数,应该是 10−(10/2+10/3)+(10/6) 然后利用二进制枚举子集个数,奇数加偶数减. 具体看代码: #include <stdio.h> #include <cstring> #incl…
题目:http://acm.hdu.edu.cn/showproblem.php?pid=4548 Problem Description 小明对数的研究比较热爱,一谈到数,脑子里就涌现出好多数的问题,今天,小明想考考你对素数的认识. 问题是这样的:一个十进制数,如果是素数,而且它的各位数字和也是素数,则称之为“美素数”,如29,本身是素数,而且2+9 = 11也是素数,所以它是美素数. 给定一个区间,你能计算出这个区间内有多少个美素数吗?   Input 第一行输入一个正整数T,表示总共有T组…
Description Some positive integers can be represented by a sum of one or more consecutive prime numbers. How many such representations does a given positive integer have? For example, the integer 53 has two representations 5 + 7 + 11 + 13 + 17 and 53…
Largest prime factor Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 8976    Accepted Submission(s): 3191 Problem Description Everybody knows any number can be combined by the prime number. Now…
http://acm.hdu.edu.cn/showproblem.php?pid=5104 找元组数量,满足p1<=p2<=p3且p1+p2+p3=n且都是素数 不用素数打表都能过,数据弱的一比 #include <cstdio> #include <cstdlib> #include <cmath> #include <cstring> #include <string> #include <queue> #inclu…
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…
第一眼看这道题目的时候觉得可能会很难也看不太懂,但是看了给出的Hint之后思路就十分清晰了 Consider the first sample. Overall, the first sample has 3 queries. The first query l = 2, r = 11 comes. You need to count f(2) + f(3) + f(5) + f(7) + f(11) = 2 + 1 + 4 + 2 + 0 = 9. The second query comes…
Twin Prime Conjecture Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Problem Description If we define dn as: dn = pn+1-pn, where pi is the i-th prime. It is easy to see that d1 = 1 and dn=even for n>1. Twin Prime…
解题思路:给定一个数,判定它由几个连续的素数构成,输出这样的种数 用的筛法素数打表 Sum of Consecutive Prime Numbers Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 20020   Accepted: 10966 Description Some positive integers can be represented by a sum of one or more consecutive…
ZOJ:http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=312 POJ:http://poj.org/problem?id=1595 题目大意: 给你两个数n和c,如果1~n(包括1和n)之间的素数个数为偶数个,则输出中间c*2个素数否则输出中间c*2-1个素数. 思路: 呀呀呀,玩了一天了,A道水题洗洗睡吧. 直接筛选素数打表. 注意c比1~n的个数大的情况要把1~n中所以素数输出. OK,然后这题1也算素数.. #incl…