codeforces 355(Div 2)C. Vanya and Label(思维,预处理)

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题目链接:

http://codeforces.com/problemset/problem/677/C


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 base64 and got new word. Now Vanya thinks of some strings and wants to know the number of pairs of words of length|s| (length of s), such that their bitwise AND is equal tos. As this number can be large, output it modulo109 + 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 from0 to 9;
  • letters from 'A' to 'Z' correspond to integers from10 to 35;
  • letters from 'a' to 'z' correspond to integers from36 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 strings 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

题意:给定一种特定的64进制如下:
  • digits from '0' to '9' correspond to integers from0 to 9;
  • letters from 'A' to 'Z' correspond to integers from10 to 35;
  • letters from 'a' to 'z' correspond to integers from36 to 61;
  • letter '-' correspond to integer 62;
  • letter '_' correspond to integer 63.
现给你一个字符串,每个字符对应64进制里面的特定的数,求有多少对相同长度字符串能够做按位与运算得到所给的字符串。

解题思路:
其实目的很明确,就是求出每个字符对应的数,可以由多少对字符所对应的数按位与得到 ,再将每个字符的可能结果乘起来就可以得出整个字符串的可能结果。
我是利用了map的性质,把字符作为map数组的下标去处理,感觉直观很多。

代码如下:
#include<iostream>#include<algorithm>#include<cstdio>#include<cstring>#include<set>#include<cmath>#include<vector>#include<map>using namespace std;const int maxn = 1e+5 + 10;char str[maxn];typedef long long ll;char ss[]= {"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_"};map<char,int>ma;const int mod = 1e+9 + 7;int main(){    ma.clear();    scanf("%s",str);    for(int i = 0; ss[i]; i++)    {        for(int j = 0; ss[j]; j++)            ma[ss[i&j]]++;    }    ll ans = 1;    for(int i = 0 ; str[i] ; i ++)    {//        cout << ma[str[i]] <<endl;        ans = ans*ma[str[i]]%mod;    }    cout << ans <<endl;    return 0 ;}




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