Problem40

原题：

An irrational decimal(无理小数) fraction is created by concatenating the positive integers:
0.123456789101112131415161718192021...
It can be seen that the 12(th) digit of the fractional part is 1.

If d(n) represents the n(th) digit of the fractional part,
find the value of the following expression.

 

分析：

该小数的小数部分是有自然数序列连接而成

 

代码：

public class Problem40 { static List<Integer> numberList = new ArrayList<Integer>(); static void putNaturalIntoList(String natural){ char[] naturalC = natural.toCharArray(); for(char c:naturalC){ numberList.add(c-'0'); } } public static void main(String[] args) { int count = 1; do{ putNaturalIntoList(String.valueOf(count)); count++; }while(numberList.size()<1000000); System.out.println(numberList.get(0) * numberList.get(99) * numberList.get(999) * numberList.get(9999) * numberList.get(99999) * numberList.get(999999)); } }