[POJ] #1003# Hangover : 浮點數運算

一. 題目

Hangover

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 116593		Accepted: 56886

Description

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.

Input

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.

Output

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.

Sample Input

1.00
3.71
0.04
5.19
0.00

Sample Output

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

Source

Mid-Central USA 2001

 

二. 題意

• 按照固定的累加方式：從高層到低層，相對於其相鄰下層能夠伸出的長度爲(1/2),(1/3),...,(1/n)
• 給定一個指定長度 S，問最少須要累加多上塊板，使其相對於桌面的伸出長度大於或等於 S

三. 分析

• 算法核心: 此題比較簡單，無需考慮任何算法
• 實現細節: 簡單的浮點數累加運算便可

四. 題解

 1 #include <stdio.h>
 2 
 3 int main()
 4 {
 5     int i;
 6     float length, sum;
 7 
 8     while (1) {
 9         sum = 0;
10         scanf("%f\n", &length);
11         if (!length) break;
12 
13         for (i = 2; ; i++) {
14             sum += (1 / (float)i);
15 
16             if (sum >= length) {
17                 printf("%d card(s)\n", i - 1);
18                 break;
19             }
20         }
21     }
22 
23     return 0;
24 }