7.3.6 pi

pi

Time Limit: 6000/2000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 47 Accepted Submission(s): 27

Problem Description

计算圆周率到小数点后5n 位。（本题不可打表）

 

Input

正整数n<300. n=0结束.

 

Output

圆周率pi到小数点后5n位.第1行输出3.以5个数为1段.每行最多10段,每段占6列,右对齐.参看Sample

 

Sample Input

20
15
0

 

Sample Output

3.
 14159 26535 89793 23846 26433 83279 50288 41971 69399 37510
 58209 74944 59230 78164 06286 20899 86280 34825 34211 70679
3.
 14159 26535 89793 23846 26433 83279 50288 41971 69399 37510
 58209 74944 59230 78164 06286

好像是用什么麦金公式，我也不知道，
http://blog.sina.com.cn/s/blog_a389f34a01013c11.html

import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Scanner;


public class Main {
    public static void main(String[] args) {
        BigDecimal TWO=BigDecimal.valueOf(2);
        BigDecimal ans=BigDecimal.valueOf(2);
        for(int i=5000;i>=1;i--){
            ans=TWO.add(ans.multiply(td(i)).divide(td(2*i+1),1800,BigDecimal.ROUND_HALF_UP));
        }
        String stra=ans.toString();
        Scanner sc=new Scanner(System.in);
        while(sc.hasNext()){
            int n=sc.nextInt();
            if(n==0)break;
            System.out.println("3.");
            for(int i=0;i<n;i++){
                System.out.print(" ");
                System.out.print(stra.substring(i*5+2,i*5+7));
                if((i+1)%10==0)System.out.println();
            }
            if(n%10!=0)System.out.println();
            
        }
    }
    public static BigDecimal td(int n){
        return BigDecimal.valueOf(n);
    }
}