博客
关于我
1093 Count PAT‘s (25分) 含DP做法
阅读量:376 次
发布时间:2019-03-05

本文共 1694 字,大约阅读时间需要 5 分钟。

1093 Count PAT’s (25分)

The string APPAPT contains two PAT’s as substrings. The first one is formed by the 2nd, the 4th, and the 6th characters, and the second one is formed by the 3rd, the 4th, and the 6th characters.

Now given any string, you are supposed to tell the number of PAT’s contained in the string.

Input Specification:

Each input file contains one test case. For each case, there is only one line giving a string of no more than 10 ^ ​5 characters containing only P, A, or T.

Output Specification:

For each test case, print in one line the number of PAT’s contained in the string. Since the result may be a huge number, you only have to output the result moded by 1000000007.

Sample Input:

APPAPT

Sample Output:

2

方法一:题目意思就是找出一个A左边的P个数*右边的T,构造两个数组分别存储在字符串i位置左边P的个数和右边T的个数,然后遍历字符串将合理位置的两个数组的数乘起来相加即可,不要忘了最后模1000000007,设字符串长度N ,整个复杂度就是遍历了三遍字符串所以还是O(N)的,不会超时。这种做法比较直接,也比较容易想到

AC代码

#include
#include
#include
using namespace std;#define N 1000000007typedef long long LL;string m;int main(){ LL res=0; cin >> m; vector
a(m.size(),0); vector
b(m.size(),0); for(int i=1;i
=0;i--) if(m[i+1]=='T') b[i]=b[i+1]+1; else b[i]=b[i+1]; for(int i=0;i

方法二:DP

#include
#include
#include
using namespace std;#define N 1000000007char s[100010],p[]=" PAT";int f[100010][4];int main(){ cin >> s+1; int n=strlen(s+1); f[0][0]=1; for(int i=1;i<=n;i++) for(int j=0;j<=3;j++) { f[i][j]=f[i-1][j]; if(s[i]==p[j]) f[i][j]=(f[i][j]+f[i-1][j-1])%N; } cout << f[n][3]; return 0;}

转载地址:http://azbwz.baihongyu.com/

你可能感兴趣的文章
mysql 导入导出大文件
查看>>
mysql 将null转代为0
查看>>
mysql 常用
查看>>
MySQL 常用列类型
查看>>
mysql 常用命令
查看>>
Mysql 常见ALTER TABLE操作
查看>>
mysql 往字段后面加字符串
查看>>
mysql 快速自增假数据, 新增假数据,mysql自增假数据
查看>>
Mysql 报错 Field 'id' doesn't have a default value
查看>>
MySQL 报错:Duplicate entry 'xxx' for key 'UNIQ_XXXX'
查看>>
mysql 排序id_mysql如何按特定id排序
查看>>
Mysql 提示:Communication link failure
查看>>
mysql 插入是否成功_PDO mysql:如何知道插入是否成功
查看>>
Mysql 数据库InnoDB存储引擎中主要组件的刷新清理条件:脏页、RedoLog重做日志、Insert Buffer或ChangeBuffer、Undo Log
查看>>
mysql 数据库备份及ibdata1的瘦身
查看>>
MySQL 数据库备份种类以及常用备份工具汇总
查看>>
mysql 数据库存储引擎怎么选择?快来看看性能测试吧
查看>>
MySQL 数据库操作指南:学习如何使用 Python 进行增删改查操作
查看>>
MySQL 数据库的高可用性分析
查看>>
Mysql 数据库重置ID排序
查看>>