hdu 4279"Number"（数论）

题意: 定义函数F(x) : 区间[1,x]上的y是满足:GCD(x,y)>1 && x%y>0的 y的个数. 问:对于任意区间[l,r] 上的F(l···r) 有几个函数值是奇数的. 打表找规律. 打的是[1,x]区间的结果 把所有结果不相同的值打出来(因为结果是递增的,所以只观察不相同的结果) 发现:ans = x/2-2 || x/2-1 再把所有结果不同 && x/2-1的值打出来 发现 sqrt(x) &1 == 1 得到:ans = x/2-

转载请注明出处:http://blog.csdn.net/u012860063?viewmode=contents 题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=4279 HDU集训队选拔赛地点:3教3楼机房,时间:5月10日(周六)12:00开始,请相互转告,谢谢~ 百度之星编程大赛--您报名了吗? Number Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768

题目描述 首先定义"special number": 如果对于一个数字B,存在一个数字A(0<A<=B),并同时满足 B%A=0 和 gcd(A,B) != 1 ,那么我们就说A是B的"special number". 再定义一个函数f(x)表示x的"special number"的数量.并且如果f(x)%2=1时,我们就称x为"real number". 现在给你两个数字x和y且1<=x<=y<

题目大意: Here are two numbers A and B (0 < A <= B). If B cannot be divisible by A, and A and B are not co-prime numbers, we define A as a special number of B. For each x, f(x) equals to the amount of x's special numbers. For example, f(6)=1, because 6

Number Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 4288    Accepted Submission(s): 1066 Problem Description Here are two numbers A and B (0 < A <= B). If B cannot be divisible by A, and A

HDU 4937 Lucky Number 题目链接 题意:给定一个数字,求它再x进制下,每位进制位上都只有3,4,5,6,求这样的x有多少种,如果无限种输出-1 思路:首先3 4 5 6特判掉是无限的,很容易想到就不证明了,然后就是枚举数字的最后一位3,4,5,6,然后进制数肯定来自这个数字的因子,因为剩下的数字肯定是a1x^1 + a2x^2 + a3x^3...这样的,这样只要在因子中找进制,去判断即可.找因子的方法用先分解再dfs找,直接试除会超时 代码: #include <cstdi

HDU 1005 Number Sequence(数论) Problem Description: A number sequence is defined as follows:f(1) = 1, f(2) = 1, f(n) = (A * f(n - 1) + B * f(n - 2)) mod 7. Given A, B, and n, you are to calculate the value of f(n). Input The input consists of multiple

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5014 Number Sequence Problem Description There is a special number sequence which has n+1 integers. For each number in sequence, we have two rules: ● ai ∈ [0,n] ● ai ≠ aj( i ≠ j ) For sequence a and sequ

题意:就是要你来找出b数组在a数组中最先匹配的位置,如果没有则输出-1 思路:直接KMP算法(算法具体思想这位牛写的不错http://blog.csdn.net/v_july_v/article/details/7041827) AC代码: #include<cstdio> #include<cstring> #include<stdlib.h> #include<iostream> using namespace std; #define maxn 100