A - Farey Sequence Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Practice POJ 2478 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 &l…

 名字是法雷数列其实是欧拉phi函数              Farey Sequence Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 11246   Accepted: 4363 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 <…

Farey Sequence Time Limit: 1000MS   Memory Limit: 65536K       Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 < a < b <= n and gcd(a,b) = 1 arranged in increasing order. Th…

http://poj.org/problem?id=2478 求欧拉函数的模板. 初涉欧拉函数,先学一学它主要的性质. 1.欧拉函数是求小于n且和n互质(包含1)的正整数的个数. 记为φ(n). 2.欧拉定理:若a与n互质.那么有a^φ(n) ≡ 1(mod n),经经常使用于求幂的模. 3.若p是一个质数,那么φ(p) = p-1.注意φ(1) = 1. 4.欧拉函数是积性函数: 若m与n互质,那么φ(nm) = φ(n) * φ(m). 若n = p^k且p为质数,那么φ(n) = p^k…

hdu1787,直接求欧拉函数 #include <iostream> #include <cstdio> using namespace std; int n; int phi(int n){ int ans=n; for(int i=2; i*i<=n; i++) if(n%i==0){ ans -= ans / i; while(n%i==0) n /= i; } if(n>1) ans -= ans / n; return ans; } int main(){…

http://poj.org/problem?id=2478 http://acm.hdu.edu.cn/showproblem.php?pid=2824 欧拉函数模板裸题,有两种方法求出所有的欧拉函数,一是筛法,而是白书上的筛法. 首先看欧拉函数的性质: 欧拉函数是求小于n且和n互质(包括1)的正整数的个数.记为φ(n). 欧拉定理:若a与n互质,那么有a^φ(n) ≡ 1(mod n),经常用于求乘法逆元. 若p是一个质数,那么φ(p) = p-1,注意φ(1) = 1. 欧拉函数是积性函数…

题目链接:http://poj.org/problem?id=2478 Farey Sequence Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 19736   Accepted: 7962 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with…

题目链接:http://poj.org/problem?id=2478 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 < a < b <= n and gcd(a,b) = 1 arranged in increasing order. The first few are F2 = {1/2}…

Farey Sequence Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 12802   Accepted: 4998 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 < a < b <= n and gcd(a,b)…

Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 15023   Accepted: 5962 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b with 0 < a < b <= n and gcd(a,b) = 1 arranged in…