In number theory, Euler's totient function φ(n) counts the positive integers up to a given integer n that are relatively prime to n. It can be defined more formally as the number of integers k in the range 1≤k≤n for which the greatest common divisor…

== oeis: 点击打开链接 瞎了,x.mod(BigInteger.ValueOf(2)).equal( BigInteger.ValueOf(1)) 写成了 x.mod(BigInteger.ValueOf(2)).equal( 1 ) T^T100块没了.. . import java.math.*; import java.util.*; import static java.lang.System.out; import java.io.*; public class Main {…

由0和1组成的串中,不能表示为由几个相同的较小的串连接成的串,称为本原串,有多少个长为n(n<=100000000)的本原串? 答案mod2008. 例如,100100不是本原串,因为他是由两个100组成,而1101是本原串. Input 输入包括多个数据,每个数据一行,包括一个整数n,代表串的长度. Output 对于每个测试数据,输出一行,代表有多少个符合要求本原串,答案mod2008. Sample Input 1 2 3 4 Sample Output 2 2 6 12 解析: 考虑所有…

HazelFan is given two positive integers a,b, and he wants to calculate amodb. But now he forgets the value of b and only remember the value of a, please tell him the number of different possible results. Input The first line contains a positive integ…

Problem Description Now given two kinds of coins A and B,which satisfy that GCD(A,B)=1.Here you can assume that there are enough coins for both kinds.Please calculate the maximal value that you cannot pay and the total number that you cannot pay. Inp…

Couple doubi 题目链接: http://acm.hust.edu.cn/vjudge/contest/121334#problem/D Description DouBiXp has a girlfriend named DouBiNan.One day they felt very boring and decided to play some games. The rule of this game is as following. There are k balls on th…

Nim or not Nim? Time Limit:1000MS     Memory Limit:32768KB     64bit IO Format:%I64d & %I64u Submit Status Practice HDU 3032 Description Nim is a two-player mathematic game of strategy in which players take turns removing objects from distinct heaps.…

Permutation Bo 题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=5753 Description There are two sequences h1∼hn and c1∼cn. h1∼hn is a permutation of 1∼n. particularly, h0=hn+1=0. We define the expression [condition] is 1 when condition is True,is 0 whe…

SG打表找规律 HDU 5795 题目连接 #include<iostream> #include<cstdio> #include<cmath> #include<algorithm> #include<cstring> using namespace std; #define MAXN 10000 int sg[MAXN],visit[MAXN]; int getsg(int n) { int i,j; ) return sg[n]; mem…

题解: 考场上靠打表找规律切的题,不过严谨的数学推导才是本题精妙所在:求:$\sum\prod_{i=1}^{m}F_{a{i}}$ 设 $f(i)$ 为 $N=i$ 时的答案,$F_{i}$ 为斐波那契数列第 $i$ 项.由于 $a$ 序列是有序的,要求的答案可以表示成:$f(i)=\sum_{j=1}^{i}f(j)*F_{i-j}$由于斐波那契数列第 0 项是 0,显然可以表示成:$f(i)=\sum_{j=1}^{i-1}f(j)*F_{i-j}$考虑一下 $f(i+1)$ 和 $f(i…