A square-free integer is an integer which is indivisible by any square number except 11. For example, 6 = 2 \cdot 36=2⋅3 is square-free, but 12 = 2^2 \cdot 312=22⋅3 is not, because 2^222 is a square number. Some integers could be decomposed into prod…

SUM 题意:f(n)是n可以拆成多少组n=a*b,a和b都是不包含平方因子的方案数目,对于a!=b,n=a*b和n=b*a算两种方案,求∑i=1nf(i) 首先我们可以知道,n=1时f(1)=1, 然后我们继续分析,当n为素数p时,只能拆成n=1*p和n=p*1这两种,所以f(p)=2, 而当n=两个质数的乘积时,对于n=左*右,p1跟p2可以任意分配在左和右,它们的方案是类乘的,所以f(p1*p2)=f(p1)*f(p2) 这里可以看出f(n)是个积性函数,那说明我们可以把它通过线性筛筛出来…

A square-free integer is an integer which is indivisible by any square number except 11. For example, 6 = 2 \cdot 36=2⋅3 is square-free, but 12 = 2^2 \cdot 312=22⋅3 is not, because 2^222 is a square number. Some integers could be decomposed into prod…

J. Sum 26.87% 1000ms 512000K   A square-free integer is an integer which is indivisible by any square number except 11. For example, 6 = 2 \cdot 36=2⋅3 is square-free, but 12 = 2^2 \cdot 312=22⋅3 is not, because 2^222 is a square number. Some integer…

G. Lpl and Energy-saving Lamps 42.07% 1000ms 65536K   During tea-drinking, princess, amongst other things, asked why has such a good-natured and cute Dragon imprisoned Lpl in the Castle? Dragon smiled enigmatically and answered that it is a big secre…

轻轻松松也能拿到区域赛名额,CCPC真的好难 An Olympian Math Problem 问答 只看题面 54.76% 1000ms 65536K   Alice, a student of grade 66, is thinking about an Olympian Math problem, but she feels so despair that she cries. And her classmate, Bob, has no idea about the problem. T…

ACM-ICPC 2018 南京赛区网络预赛 A. An Olympian Math Problem 计算\(\sum_{i=1}^{n-1}i\cdot i!(MOD\ n)\) \(\sum_{i=1}^{n-1}i\cdot i! = \sum_{i=1}^{n-1}[(i+1)!-i!](MOD\ n)=n!-1!(MOD\ n)=n-1\) #include<bits/stdc++.h> using namespace std; int T; long long n; int mai…

ACM-ICPC 2018 南京赛区网络预赛 E题 题目链接: https://nanti.jisuanke.com/t/30994 Dlsj is competing in a contest with n (0 < n \le 20)n(0<n≤20) problems. And he knows the answer of all of these problems. However, he can submit ii-th problem if and only if he has s…

题目链接:https://nanti.jisuanke.com/t/30991 Feeling hungry, a cute hamster decides to order some take-away food (like fried chicken for only 3030 Yuan). However, his owner CXY thinks that take-away food is unhealthy and expensive. So she demands her hams…

A. An Olympian Math Problem 54.28% 1000ms 65536K   Alice, a student of grade 66, is thinking about an Olympian Math problem, but she feels so despair that she cries. And her classmate, Bob, has no idea about the problem. Thus he wants you to help him…