Codeforces Round #289 (Div. 2, ACM ICPC Rules) E. Pretty Song 算贡献+前缀和
1 second
256 megabytes
standard input
standard output
When Sasha was studying in the seventh grade, he started listening to music a lot. In order to evaluate which songs he likes more, he introduced the notion of the song's prettiness. The title of the song is a word consisting of uppercase Latin letters. The prettiness of the song is the prettiness of its title.
Let's define the simple prettiness of a word as the ratio of the number of vowels in the word to the number of all letters in the word.
Let's define the prettiness of a word as the sum of simple prettiness of all the substrings of the word.
More formally, let's define the function vowel(c) which is equal to 1, if c is a vowel, and to 0 otherwise. Let si be the i-th character of string s, and si..j be the substring of word s, staring at the i-th character and ending at the j-th character (sisi + 1... sj, i ≤ j).
Then the simple prettiness of s is defined by the formula:

The prettiness of s equals

Find the prettiness of the given song title.
We assume that the vowels are I, E, A, O, U, Y.
The input contains a single string s (1 ≤ |s| ≤ 5·105) — the title of the song.
Print the prettiness of the song with the absolute or relative error of at most 10 - 6.
IEAIAIO
28.0000000
BYOB
5.8333333
YISVOWEL
17.0500000
In the first sample all letters are vowels. The simple prettiness of each substring is 1. The word of length 7 has 28 substrings. So, the prettiness of the song equals to 28.
题目链接:http://codeforces.com/contest/509/problem/E
题意:给你一个字符串,求字串中I, E, A, O, U, Y.的比例和;
例如:BYOB
B 0 BY 1/2 BYO 2/3 BYOB 1/2
Y 1 YO 1 YOB 2/3
O 1 OB 1/2
B 0
0+1+1/2+2/3+1/2+1+1+2/3+1+1/2+0=5.833333
思路:显然算贡献的题;
对于一个字符,左边有l个,右边有r个,包含其的字串总有(l+1)*(r+1)个;
其贡献会形成一个平行四边行
1 1/2 1/3 1/4
1/2 1/3 1/4 1/5
用前缀和预处理即可;
#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<cstdio>
#include<cmath>
#include<string>
#include<queue>
#include<algorithm>
#include<stack>
#include<cstring>
#include<vector>
#include<list>
#include<set>
#include<map>
using namespace std;
#define ll long long
#define pi (4*atan(1.0))
#define mk make_pair
#define eps 1e-7
#define bug(x) cout<<"bug"<<x<<endl;
const int N=5e5+,M=1e6+,inf=;
const ll INF=1e18+,mod=; /// 数组大小
char ch[]={'I','E','A','O','U','Y'},s[N];
double sum1[N],sum2[N],sum3[N];
int check(char a)
{
for(int i=;i<;i++)
if(a==ch[i])return ;
return ;
}
int main()
{
scanf("%s",s+);
int n=strlen(s+);
for(int i=;i<=n;i++)
sum1[i]=sum1[i-]+(1.0*/i);
for(int i=;i<=n;i++)
sum2[i]=sum2[i-]+sum1[i];
for(int i=n,j=;i>=;i--,j++)
sum3[j]=sum3[j-]+sum1[n]-sum1[i-];
double ans=0.0;
for(int i=;i<=n;i++)
{
if(check(s[i]))
{
int l=i;
int r=n-i+;
ans+=1.0*sum1[n]*l;
ans-=sum2[l-];
ans-=sum3[l-];
}
//cout<<ans<<endl;
}
printf("%f\n",ans);
return ;
}
1 second
256 megabytes
standard input
standard output
When Sasha was studying in the seventh grade, he started listening to music a lot. In order to evaluate which songs he likes more, he introduced the notion of the song's prettiness. The title of the song is a word consisting of uppercase Latin letters. The prettiness of the song is the prettiness of its title.
Let's define the simple prettiness of a word as the ratio of the number of vowels in the word to the number of all letters in the word.
Let's define the prettiness of a word as the sum of simple prettiness of all the substrings of the word.
More formally, let's define the function vowel(c) which is equal to 1, if c is a vowel, and to 0 otherwise. Let si be the i-th character of string s, and si..j be the substring of word s, staring at the i-th character and ending at the j-th character (sisi + 1... sj, i ≤ j).
Then the simple prettiness of s is defined by the formula:

The prettiness of s equals

Find the prettiness of the given song title.
We assume that the vowels are I, E, A, O, U, Y.
The input contains a single string s (1 ≤ |s| ≤ 5·105) — the title of the song.
Print the prettiness of the song with the absolute or relative error of at most 10 - 6.
IEAIAIO
28.0000000
BYOB
5.8333333
YISVOWEL
17.0500000
In the first sample all letters are vowels. The simple prettiness of each substring is 1. The word of length 7 has 28 substrings. So, the prettiness of the song equals to 28.
Codeforces Round #289 (Div. 2, ACM ICPC Rules) E. Pretty Song 算贡献+前缀和的更多相关文章
- codeforces水题100道 第十八题 Codeforces Round #289 (Div. 2, ACM ICPC Rules) A. Maximum in Table (brute force)
题目链接:http://www.codeforces.com/problemset/problem/509/A题意:f[i][1]=f[1][i]=1,f[i][j]=f[i-1][j]+f[i][j ...
- Codeforces Round #289 (Div. 2, ACM ICPC Rules) A. Maximum in Table【递推】
A. Maximum in Table time limit per test 2 seconds memory limit per test 256 megabytes input standard ...
- 贪心 Codeforces Round #289 (Div. 2, ACM ICPC Rules) B. Painting Pebbles
题目传送门 /* 题意:有 n 个piles,第 i 个 piles有 ai 个pebbles,用 k 种颜色去填充所有存在的pebbles, 使得任意两个piles,用颜色c填充的pebbles数量 ...
- 递推水题 Codeforces Round #289 (Div. 2, ACM ICPC Rules) A. Maximum in Table
题目传送门 /* 模拟递推水题 */ #include <cstdio> #include <iostream> #include <cmath> #include ...
- Codeforces Round #622 (Div. 2) B. Different Rules(数学)
Codeforces Round #622 (Div. 2) B. Different Rules 题意: 你在参加一个比赛,最终按两场分赛的排名之和排名,每场分赛中不存在名次并列,给出参赛人数 n ...
- Codeforces Round #289 Div 2
A. Maximum in Table 题意:给定一个表格,它的第一行全为1,第一列全为1,另外的数满足a[i][j]=a[i-1][j]+a[i][j-1],求这个表格中的最大的数 a[n][n]即 ...
- Codeforces Round #554 (Div. 2) F2. Neko Rules the Catniverse (Large Version) (矩阵快速幂 状压DP)
题意 有nnn个点,每个点只能走到编号在[1,min(n+m,1)][1,min(n+m,1)][1,min(n+m,1)]范围内的点.求路径长度恰好为kkk的简单路径(一个点最多走一次)数. 1≤n ...
- Codeforces Round #381 (Div. 1) B. Alyona and a tree dfs序 二分 前缀和
B. Alyona and a tree 题目连接: http://codeforces.com/contest/739/problem/B Description Alyona has a tree ...
- Codeforces Round #294 (Div. 2) D. A and B and Interesting Substrings [dp 前缀和 ]
传送门 D. A and B and Interesting Substrings time limit per test 2 seconds memory limit per test 256 me ...
随机推荐
- [LeetCode] 331. Verify Preorder Serialization of a Binary Tree_Medium tag: stack
One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, ...
- word2vec原理(一) CBOW+Skip-Gram模型基础
word2vec是google在2013年推出的一个NLP工具,它的特点是将所有的词向量化,这样词与词之间就可以定量的去度量他们之间的关系,挖掘词之间的联系.本文的讲解word2vec原理以Githu ...
- VMWARE安装centos6 http://www.centoscn.com/image-text/setup/2013/0816/1263.html
http://www.centoscn.com/image-text/setup/2013/0816/1263.html
- linux lvs
- Python: 字典列表: 通过某个字段将记录分组
问题:有一个字典或者实例的序列,想根据某个特定的字段比如date 来分组迭代访问. answer: itertools.groupby函数对于这样的数据分组操作非常实用 eg: rows = [{'a ...
- Selenium2+python自动化54-unittest生成测试报告(HTMLTestRunner)
前言 批量执行完用例后,生成的测试报告是文本形式的,不够直观,为了更好的展示测试报告,最好是生成HTML格式的. unittest里面是不能生成html格式报告的,需要导入一个第三方的模块:HTMLT ...
- Linux基础命令---eject
eject eject指令允许在软件控制下弹出可移动媒体(通常是光盘.软盘.磁带或Jaz或ZIP磁盘).该命令还可以控制一些由某些设备支持的自动弹出功能的多光盘转换器,并关闭一些光盘驱动器的盘. 对应 ...
- ELK学习笔记之CentOS 7下ELK(6.2.4)++LogStash+Filebeat+Log4j日志集成环境搭建
0x00 简介 现在的公司由于绝大部分项目都采用分布式架构,很早就采用ELK了,只不过最近因为额外的工作需要,仔细的研究了分布式系统中,怎么样的日志规范和架构才是合理和能够有效提高问题排查效率的. 经 ...
- P1661 扩散
P1661 扩散 二分+最小生成树(kruskal使用并查集) 不清楚的题意导致我被坑了qwq,其实间接联通也是允许的.所以可以使用并查集+最小生成树维护 每次二分答案,然后跑一遍最小生成树判断是否联 ...
- YAML配置文件
最近,研究jeeweb这个框架,发现新版本中的配置文件都是用的.yml为后缀的文件,打开一看,和以前的xml和properties语法有很大区别,因此仔细研究一下. 简介: YAML是(YAML Ai ...