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.