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Codeforces 677C. Vanya and Label 位操作

C. Vanya and Label
time limit per test:1 second
memory limit per test:256 megabytes
input:standard input
output:standard output

While walking down the street Vanya saw a label "Hide&Seek". Because he is a programmer, he used & as a bitwise AND for these two words represented as a integers in base 64 and got new word. Now Vanya thinks of some string s and wants to know the number of pairs of words of length |s| (length of s), such that their bitwise AND is equal to s. As this number can be large, output it modulo 109 + 7.

To represent the string as a number in numeral system with base 64 Vanya uses the following rules:

  • digits from '0' to '9' correspond to integers from 0 to 9;
  • letters from 'A' to 'Z' correspond to integers from 10 to 35;
  • letters from 'a' to 'z' correspond to integers from 36 to 61;
  • letter '-' correspond to integer 62;
  • letter '_' correspond to integer 63.
Input

The only line of the input contains a single word s (1 ≤ |s| ≤ 100 000), consisting of digits, lowercase and uppercase English letters, characters '-' and '_'.

Output

Print a single integer — the number of possible pairs of words, such that their bitwise AND is equal to string s modulo 109 + 7.

Examples
Input
z
Output
3
Input
V_V
Output
9
Input
Codeforces
Output
130653412
Note

For a detailed definition of bitwise AND we recommend to take a look in the corresponding article in Wikipedia.

In the first sample, there are 3 possible solutions:

  1. z&_ = 61&63 = 61 = z
  2. _&z = 63&61 = 61 = z
  3. z&z = 61&61 = 61 = z
 
传送门:http://codeforces.com/contest/677/problem/C

 

题意:一个字符串s,字符串的每个字母代表一种数字。问多少种的等长的字符串通过&操作得到s。

思路:1&0=0,0&1=0,0&0=0,1&1=1。字符串里面的每一个字符ch的每一位与1 &操作,如果得到0就有3就情况,如果得到1只有一种情况。[0,63]的2进制最多有6位。

代码:

#include<bits/stdc++.h>
using namespace std;
const int mod = 1e9+7;
char s[100100];
int getidx(char c)
{
    if(c>='0'&&c<='9') return c-'0';
    if(c>='A'&&c<='Z') return c-'A'+10;
    if(c>='a'&&c<='z') return c-'a'+36;
    if(c=='-') return 62;
    if(c=='_') return 63;
}
int main()
{
    int i,j;
    scanf("%s",s);
    __int64 ans = 1;
    for(i=0; i<strlen(s); i++)
    {
        int p = getidx(s[i]);
        for(j=0; j<6; j++)
            if(((p>>j)&1)==0) ans=ans*3%mod;
    }
    cout<<ans<<endl;
}
位操作

 

posted on 2016-08-04 11:23  GeekZRF  阅读(218)  评论(0编辑  收藏  举报

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