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
MyPython
查看>>
MTD技术介绍
查看>>
MySQL
查看>>
MySQL
查看>>
mysql
查看>>
MTK Android 如何获取系统权限
查看>>
MySQL - 4种基本索引、聚簇索引和非聚索引、索引失效情况、SQL 优化
查看>>
MySQL - ERROR 1406
查看>>
mysql - 视图
查看>>
MySQL - 解读MySQL事务与锁机制
查看>>
MTTR、MTBF、MTTF的大白话理解
查看>>
mt_rand
查看>>
mysql -存储过程
查看>>
mysql /*! 50100 ... */ 条件编译
查看>>
mudbox卸载/完美解决安装失败/如何彻底卸载清除干净mudbox各种残留注册表和文件的方法...
查看>>
mysql 1264_关于mysql 出现 1264 Out of range value for column 错误的解决办法
查看>>
mysql 1593_Linux高可用(HA)之MySQL主从复制中出现1593错误码的低级错误
查看>>
mysql 5.6 修改端口_mysql5.6.24怎么修改端口号
查看>>
MySQL 8.0 恢复孤立文件每表ibd文件
查看>>
MySQL 8.0开始Group by不再排序
查看>>