No.2017：Speed Limit

Speed Limit
Time Limit:1000MS  Memory Limit:30000K
Total Submit:2997 Accepted:2094

Description
Bill and Ted are taking a road trip. But the odometer in their car is broken, so they don't know how many miles they have driven. Fortunately, Bill has a working stopwatch, so they can record their speed and the total time they have driven. Unfortunately, their record keeping strategy is a little odd, so they need help computing the total distance driven. You are to write a program to do this computation.

For example, if their log shows

Speed in miles perhour	Total elapsed time in hours
20	2
30	6
10	7

this means they drove 2 hours at 20 miles per hour, then 6-2=4 hours at 30 miles per hour, then 7-6=1 hour at 10 miles per hour. The distance driven is then (2)(20) + (4)(30) + (1)(10) = 40 + 120 + 10 = 170 miles. Note that the total elapsed time is always since the beginning of the trip, not since the previous entry in their log.

 

Input
The input consists of one or more data sets. Each set starts with a line containing an integer n, 1 <= n <= 10, followed by n pairs of values, one pair per line. The first value in a pair, s, is the speed in miles per hour and the second value, t, is the total elapsed time. Both s and t are integers, 1 <= s <= 90 and 1 <= t <= 12. The values for t are always in strictly increasing order. A value of -1 for n signals the end of the input.

Output
For each input set, print the distance driven, followed by a space, followed by the word "miles"

Sample Input

3
20 2
30 6
10 7
2
60 1
30 5
4
15 1
25 2
30 3
10 5
-1

 

Sample Output

170 miles
180 miles
90 miles

Java实现代码：
/**//*
 * Main.java
 *
 * Created on 2006年9月15日, 上午3:37
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

/** *//**
 *
 * @author jailu
 */
import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner cin = new Scanner(System.in);
        String []strTemp;
        int []intSpeed = new int[1];
        intSpeed[0] = -1;
        int []intTime = new int[1];
        int i = 0;
        int Sum = 0;
            
        while (cin.hasNext())
        {
            String str = cin.nextLine();
            strTemp = str.split(" ");
            
            if (strTemp.length == 1)
            {
                if (intSpeed[0] != -1)
                {
                    Sum += intSpeed[0] * intTime[0];
                    for (int j = 1;j < intSpeed.length;j ++)
                    {
                        Sum += intSpeed[j] * (intTime[j] - intTime[j - 1]);
                    }
                    System.out.println(Sum + " miles");
                    Sum = 0;
                    intSpeed[0] = -1;
                }

                if (strTemp[0].equals("-1"))
                {
                    break;
                }
                
                intSpeed = new int[Integer.parseInt(strTemp[0])];
                intTime = new int[Integer.parseInt(strTemp[0])];
                i = 0;
            }
            else
            {
                intSpeed[i] = Integer.parseInt(strTemp[0]);
                intTime[i] = Integer.parseInt(strTemp[1]);
                i ++;
            }
        }
    }
}



批定结果：

    

        

            
Run ID
            
User
            
Problem
            
Result
            
Memory
            
Time
            
Language
            
Code Length
            
Submit Time
        
        

            
1586149
            
jailu
            
2017
            
Accepted
            
1300K
            
281MS
            
Java
            
1.44K
            
2006-09-15 04:29:03.0