codeforces215E(数位DP,规律水过)

地址:http://codeforces.com/contest/215/problem/E

E. Periodical Numbers
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

A non-empty string s is called binary, if it consists only of characters "0" and "1". Let's number the characters of binary string s from 1 to the string's length and let's denote the i-th character in string s as si.

Binary string s with length n is periodical, if there is an integer 1 ≤ k < n such that:

  • k is a divisor of number n
  • for all 1 ≤ i ≤ n - k, the following condition fulfills: si = si + k

For example, binary strings "101010" and "11" are periodical and "10" and "10010" are not.

A positive integer x is periodical, if its binary representation (without leading zeroes) is a periodic string.

Your task is to calculate, how many periodic numbers are in the interval from l to r (both ends are included).

Input

The single input line contains two integers l and r (1 ≤ l ≤ r ≤ 1018). The numbers are separated by a space.

Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use the cin, cout streams or the %I64dspecifier.

Output

Print a single integer, showing how many periodic numbers are in the interval from l to r (both ends are included).

Sample test(s)
input
1 10
output
3
input
25 38
output
2
Note

In the first sample periodic numbers are 37 and 10.

In the second sample periodic numbers are 31 and 36.


题意:寻找周期数,例如10的二进制是1010,是以10为循环节的周期数。

思路:通过确定第一节来找周期数,这题核心在于去重。

           例如以2个二进制数为一小节生成的周期数11 11 11 11、10 10 10 10与以4个二进制数为一小节生成的周期数1111 1111、1010 1010重复。

           自己试了多种方法,但每次都不能很好的将置顶情况与不置顶情况分开。

           看了下别人的思路,每次都重置数组来去重,略犀利。

代码:

#include
#include
#include
#include
#include
using namespace std;
#define LL __int64
LL num[100],dp[100];
LL getdp(int len,int k,LL m)  //对于置顶情况的处理
{
    LL x=0;
    for(int i=0;im);  //将极限值与限定值相比较,从而判断极值是否在限定范围内
}
LL getans(LL m)
{
    int len;
    LL n=m,ans=0;
    for(len=0;n;n>>=1) num[++len]=n&1;
    for(int i=2;i<=len;i++)
    {
        memset(dp,0,sizeof(dp));  //每次重置数组,这样可以对付多种情况。我做这题时只想到了开二进制来去重,没想到滚动更方便
        for(int j=1;j


你可能感兴趣的:(数位DP,递推)