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
Mysql8在Centos上安装后忘记root密码如何重新设置
查看>>
Mysql8在Windows上离线安装时忘记root密码
查看>>
MySQL8找不到my.ini配置文件以及报sql_mode=only_full_group_by解决方案
查看>>
mysql8的安装与卸载
查看>>
MySQL8,体验不一样的安装方式!
查看>>
MySQL: Host '127.0.0.1' is not allowed to connect to this MySQL server
查看>>
Mysql: 对换(替换)两条记录的同一个字段值
查看>>
mysql:Can‘t connect to local MySQL server through socket ‘/var/run/mysqld/mysqld.sock‘解决方法
查看>>
MYSQL:基础——3N范式的表结构设计
查看>>
MYSQL:基础——触发器
查看>>
Mysql:连接报错“closing inbound before receiving peer‘s close_notify”
查看>>
mysqlbinlog报错unknown variable ‘default-character-set=utf8mb4‘
查看>>
mysqldump 参数--lock-tables浅析
查看>>
mysqldump 导出中文乱码
查看>>
mysqldump 导出数据库中每张表的前n条
查看>>
mysqldump: Got error: 1044: Access denied for user ‘xx’@’xx’ to database ‘xx’ when using LOCK TABLES
查看>>
Mysqldump参数大全(参数来源于mysql5.5.19源码)
查看>>
mysqldump备份时忽略某些表
查看>>
mysqldump实现数据备份及灾难恢复
查看>>
mysqldump数据库备份无法进行操作只能查询 --single-transaction
查看>>