hdu5879Cure(java解法)

Cure

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1133    Accepted Submission(s): 377

Problem Description

Given an integer n, we only want to know the sum of 1/k2 where k from 1 to n.

 

Input

There are multiple cases.
For each test case, there is a single line, containing a single positive integer n. 
The input file is at most 1M.

 

Output

The required sum, rounded to the fifth digits after the decimal point.

 

Sample Input

124815

 

Sample Output

1.000001.250001.423611.527421.58044

 

Source

2016 ACM/ICPC Asia Regional Qingdao Online

 

import java.util.Scanner;public class Main {public static void main(String[] args) {// TODO Auto-generated method stubdouble num[] = new double[200000];Scanner cin = new Scanner(System.in);java.text.DecimalFormat   df   =new   java.text.DecimalFormat("#.00000");  num[0] = 0;for(int i=1;i<200000;i++){num[i] = num[i-1]+1.0/i/i;}String str;while(cin.hasNext()){str = cin.nextLine();if(str.length()<=6){int n = 0;for(int i =0 ; i<str.length();i++){n = n*10+(str.charAt(i)-'0');}if(n<=200000){System.out.println(df.format(num[n]));}elseSystem.out.println("1.64493");}elseSystem.out.println("1.64493");}}}