POJ ACM习题【No.1003】

How far can you make a stack of cards overhang a table? If you have one card, you can create a maximum overhang of half a card length. (We're assuming that the cards must be perpendicular to the table.) With two cards you can make the top card overhang the bottom one by half a card length, and the bottom one overhang the table by a third of a card length, for a total maximum overhang of 1/2 + 1/3 = 5/6 card lengths. In general you can make n cards overhang by 1/2 + 1/3 + 1/4 + ... + 1/( n + 1) card lengths, where the top card overhangs the second by 1/2, the second overhangs tha third by 1/3, the third overhangs the fourth by 1/4, etc., and the bottom card overhangs the table by 1/( n + 1). This is illustrated in the figure below.

The input consists of one or more test cases, followed by a line containing the number 0.00 that signals the end of the input. Each test case is a single line containing a positive floating-point number c whose value is at least 0.01 and at most 5.20; c will contain exactly three digits.

For each test case, output the minimum number of cards necessary to achieve an overhang of at least c card lengths. Use the exact output format shown in the examples.

    1.00
3.71
0.04
5.19
0.00

  

    3 card(s)
61 card(s)
1 card(s)
273 card(s)
  

    import java.util.*;

public class Main {

	public static void main(String[] args) {
		Scanner cin = new Scanner(System.in);
		String str;
		int maxCardNum = 0;
		
		while(cin.hasNext())
		{
			str = cin.nextLine();
			if(str.equals("0.00"))
				break;
			
			float len = Float.valueOf(str).floatValue();
			
			maxCardNum = getCardNum(len);
			System.out.println(maxCardNum + " card(s)");
		}

	}
	
	private static int getCardNum(float len)
	{
		float value = 0;
		int index = 2;
		
		while (value < len)
		{
			value += 1.0/index;
			index++;
		}
			
		return index-2;
	}

}