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(){…
Farey Sequence Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 14291 Accepted: 5647 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)…
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…
题目链接:https://vjudge.net/problem/POJ-2478 Farey Sequence Time Limit: 1000MS Memory Limit: 65536K Total Submissions: 17753 Accepted: 7112 Description The Farey Sequence Fn for any integer n with n >= 2 is the set of irreducible rational numbers a/b…
洛谷题目传送门 分数其实就是一个幌子,实际上就是求互质数对的个数(除开一个特例\((1,1)\)).因为保证了\(a<b\),所以我们把要求的东西拆开看,不就是\(\sum_{i=2}^n\phi(i)\)吗? 关于通过筛素数线性求欧拉函数的一点思路总结在蒟蒻的blog里 剩下的就是记一个前缀和了. #include<cstdio> #define R register const int N=1000001; int pr[N],phi[N]; long long ans[N]; bo…
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…
链接: https://vjudge.net/problem/POJ-2478 题意: 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} F3 =…
题目链接 Description Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz. Input There are se…
<题目链接> 题目大意: Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz. 解题分析: 其实只要看懂题目就会…
Relatives Given n, a positive integer, how many positive integers less than n are relatively prime to n? Two integers a and b are relatively prime if there are no integers x > 1, y > 0, z > 0 such that a = xy and b = xz. Input There are several t…
Bamboo Pole-vault is a massively popular sport in Xzhiland. And Master Phi-shoe is a very popular coach for his success. He needs some bamboos for his students, so he asked his assistant Bi-Shoe to go to the market and buy them. Plenty of Bamboos of…
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 <…
题目大意: 给定m n p 求下式 题解:https://blog.csdn.net/codeswarrior/article/details/81700226 莫比乌斯讲解:https://www.cnblogs.com/peng-ym/p/8647856.html 莫比乌斯的mu[]:https://www.cnblogs.com/cjyyb/p/7953803.html #include <bits/stdc++.h> using namespace std; #define LL…
Longge's problem Description Longge is good at mathematics and he likes to think about hard mathematical problems which will be solved by some graceful algorithms. Now a problem comes: Given an integer N(1 < N < 2^31),you are to calculate ∑gcd(i,…
