UVA573 The Snail

 The Snail 

A snail is at the bottom of a 6-foot well and wants to climb to the top.The snail can climb 3 feetwhile the sun is up, but slides down 1 foot at night while sleeping.The snail has a fatigue factorof 10%, which means that on each successive day the snail climbs10% 3 = 0.3 feet less thanit did the previous day. (The distance lost to fatigue is always 10% of thefirst day's climbingdistance.) On what day does the snail leave the well, i.e., what is the firstday during whichthe snail's heightexceeds 6 feet? (A day consists of a period of sunlightfollowed by a period ofdarkness.) As you can see from the following table, the snail leaves the wellduring the third day.

DayInitial HeightDistance ClimbedHeight After ClimbingHeight After Sliding10'3'3'2'22'2.7'4.7'3.7'33.7'2.4'6.1'-

Your job is to solve this problem in general. Depending on the parametersof the problem, thesnail will eventually either leave the well or slide back to the bottom ofthe well. (In other words,the snail's height will exceed the height of the well or become negative.)You must find out whichhappens first and on what day.

Input 

The input file contains one or more test cases, each on a line by itself.Each line contains fourintegersH, U, D, and F, separated by a single space. IfH= 0 it signals the end of the input;otherwise, all four numbers will be between 1 and 100, inclusive.H is theheight of the well infeet, U is the distance in feet that the snail can climb during the day,D is the distance in feetthat the snail slides down during the night, andF is the fatigue factorexpressed as a percentage.The snail never climbs a negative distance. If the fatigue factor dropsthe snail's climbing distancebelow zero, the snail does not climb at all that day. Regardless of how farthe snail climbed, it always slides D feet at night.

Output 

For each test case, output a line indicating whether the snail succeeded(left the well) or failed(slid back to the bottom) and on what day. Format the outputexactly as shown in the example.

Sample Input 

6 3 1 1010 2 1 5050 5 3 1450 6 4 150 6 3 11 1 1 10 0 0 0

Sample Output 

success on day 3failure on day 4failure on day 7failure on day 68success on day 20failure on　day 2

题目的意思就是蜗牛从井底爬上来，输入分别是井底的深度。每天爬的高度，每天掉的高度。还有每天爬的高度的减弱比例。当爬的高度大于深度（等于不算），就成功，掉到小于０（等于也不算）。减弱比例，像第一的测试数据　１０，就是１０％．第一天能爬３米，第二天就减弱１０％　，爬２．７米，每天减弱比例都是和第一天比较的，也就是每天都是少爬０．３米，但注意小于０后，都按０算。

ＡＣ代码如下：

#include<iostream>using namespace std;int main ( ) {double high,up,down,pow;double next;double dis = 0;int day = 0;int temp;while(cin >> high >> up >> down >> pow) {if (high == 0)break;pow = ( pow  / 100.0 );next = up * pow;while (1) {dis = dis + up;if (dis > high)break;dis = dis - down;if (dis < 0)break;day++;up = up - next;if (up < 0)up = 0;}if (dis < 0)cout << "failure on day "<< day + 1 <<endl;if (dis > high)cout << "success on day "<< day + 1 <<endl;dis = 0;day = 0;}return 0;}