CMSC 201
Programming Project One Solutions

General Comments

• Expected levels of documentation.
  1. Pay attention to the naming for #defines and variables
  2. Note the comment style -- the format of comments, when and where comments are provided.
  3. The file header comment
• Solutions to the problem
  If your solution is more complex than these, you need to give more thought to your prgram before you start writing code.

  Notes

  In all of these solutions, I concieved of each 6-hour time period as a "time-zone". I therefore started each relevant #define and variable with the prefix "tz". The 4 "time-zones" are
  Time-Zone 1: Midnight to 6:00 AM
  Time-Zone 2: 6:00 AM to noon
  Time-Zone 3: Noon to 6:00 PM
  Time-Zone 4: 6:00 PM to Midnight

  Each solution accumulates minutes for each time-zone within the the while loop. For efficiency, the fee is calculatedd only at the end of the program.

Solution 1 -- The brute force approach

Given the assumptions that 0 <= start time < end time <= 2359, there are 10 possible cases as listed below.

1. start time in time-zone 1 and end time in time-zone 1
2. start time in time-zone 1 and end time in time-zone 2
3. start time in time-zone 1 and end time in time-zone 3
4. start time in time-zone 1 and end time in time-zone 4
5. start time in time-zone 2 and end time in time-zone 2
6. start time in time-zone 2 and end time in time-zone 3
7. start time in time-zone 2 and end time in time-zone 4
8. start time in time-zone 3 and end time in time-zone 3
9. start time in time-zone 3 and end time in time-zone 4
10. start time in time-zone 4 and end time in time-zone 4

Solution 2 -- A simpler (but less efficent) way

In solution 2, the program loops from start time to end time. It determines to which time-zone each minute of the loop belongs, and increments the number of minutes for that time-zone. In this loop, the loop index is the time that the minute begins, which determines the fee for that minute.

Solution 3 -- a more complex but efficient sulution

• the program checks if the start time and end time are in time-zone 1.
  • If so, simply subtract them to get the answer.
  • If not, subtract the start time start from the start time of time-zone 2 to get the minutes in time-zone 1. Then "move" the start time to the beginning of time-zone 2
• check if the start time and endtime are both in time-zone 2.
  • If so, subtract them to get the minutes in time-zone 2.
  • If not, subtract the start time from the start of time-zone 3 to get the minutes in time-zone 2, then "move the start time to the beginning of time-zone 3.
• Continue this process for all time-zones.

Thursday, 24-Feb-2000 14:58:07 EST