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  • Codeforces Round #355 (Div. 2) C

    Description

    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  

    给我们一下字符串,问我们可以通过&后,值依然和题目上规定的相同

    我们当然可以先把0~63的先全部&一下,存下结果,然后,就一个字符一个字符的判断就好啦~

     1 #include<iostream>
     2 #include<stdio.h>
     3 #include<map>
     4 using namespace std;
     5 map<int,int> q;
     6 int main()
     7 {
     8     for(int i=0;i<=63;i++)
     9     {
    10         for(int j=0;j<=63;j++)
    11         {
    12             q[i&j]++;
    13         }
    14     }
    15     int pos;
    16     long long num=1;
    17     string s;
    18     cin>>s;
    19     for(int i=0;i<s.length();i++)
    20     {
    21         if(s[i]>='0'&&s[i]<='9')
    22         {
    23             pos=s[i]-'0';
    24         }
    25         else if(s[i]>='A'&&s[i]<='Z')
    26         {
    27             pos=s[i]-'A'+10;
    28         }
    29         else if(s[i]>='a'&&s[i]<='z')
    30         {
    31             pos=s[i]-'a'+36;
    32         }
    33         else if(s[i]=='-')
    34         {
    35             pos=62;
    36         }
    37         else if(s[i]=='_')
    38         {
    39             pos=63;
    40         }
    41         num=num*q[pos]%1000000007;
    42     }
    43     cout<<num<<endl;
    44     return 0;
    45 }
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  • 原文地址:https://www.cnblogs.com/yinghualuowu/p/5553312.html
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