Taxi fares

[kevgueni]

I had the following question on job interview. It took 1 hour for me to write the code for this program, but interviewer said that my design was not good. How would you do design for this problem? Any tips will be appreciated.

Background
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Taxi fares in New York City are regulated by the Taxi & Limousine Commission (TLC) and calculated by meter. The rate of fare is as follows:

- The sum of $2.50 is payable upon entry.
- $0.40 is paid for every additional unit.
- A unit fare is one-fifth of a mile when the taxicab is traveling 6 mph or more; or
- 120 seconds (at a rate of 20 cents per minute), when the taxicab is not in motion or is traveling at less than 6 mph.

There is an additional night surcharge of $0.50 after 8:00 pm and before 6:00 am. There is also a peak weekday surcharge of $1.00 after 4:00 pm and before 8:00 pm.
There are 20 New York City blocks to the mile.
Problem Definition
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You will be provided with an array of integers representing the number of blocks the cab travels a passenger’s ride. You will also be provided with a DateTime value indicating the exact moment in time when the taxi ride is considered to have begun.

You are to calculate the total fares in dollars and cents.

Return the total fare as a normally formatted USD string.

You are to expose your calculation functionality as a public instance method named Calculate. The method’s ordered parameters should be as follows:

DateTime rideStart, int[] blocksTraveled

[dannywooly]

Out of interest could you post your response?

[Retali8]

that was a job interview question...sounds more like a school test question.

[wild_bill]

How would you know how much time the cab spends doing under 6 mph?

[kebo]

I probably would of just given him a thorough flowchart (to show off my impecible organizational skills) and explained that although there are many ways to code the project, it alway has to start with the flowchart. BAM! got the job
kevin

[<ABX]

this is very real situation and it could be resolved ... but i'm not sure that it goes so easy ... actually, one hour should not be enough time to accomplish all those tasks even if you are skilled developer you can't draw up solution fairly quickly .... anyway you didn't get the job ... sorry more lucky next time

This task doesn't seem too complicated and any decent developer should be able to lay down some mock-logic in 10-15min.

The problem I find with the question is

- A unit fare is one-fifth of a mile when the taxicab is traveling 6 mph or more; or
- 120 seconds (at a rate of 20 cents per minute), when the taxicab is not in motion or is traveling at less than 6 mph.

We are not give any information on this and thus, unless me make some creative assumtions, it is not solvable.

Also, if it were to hit peak hours during a ride, would should the surcharge(s) apply?

Also, shouldn't we be provided with a time when the ride ended?

[Jacob Roman]

What I would do is make a 3D taxi-like environment using DirectX9 with it calculating in real time. Only I would add a twist to it. Crazy Taxi anyone?

BAM!

I got the job.

Anyway's, this doesn't sound like a job interview question at all. More like a school question. Job interviews involve your qualifications, your experience, your previous jobs, your educational background.... through your resume

Then your employer will just ask you questions. Once you are hired, they will usually put you through training, and show you the ropes.

Interviews can't be expressed using simple school projects like this. That's just not how the real world works.

[kevgueni]

It was online prescreen test. I may include any supplemental items or information I desire.
I did the following way:

Fare newFare = new Fare();
newFare.Calculate (rideStart, blocksTraveled) ;

I just wondering how to implement Calculate function? As an abstract, interface or overriding? How would you do it?

[szlamany]

NYC is a unique place. 10 blocks is a mile - so 1/5th a mile is two blocks.

Traffic either crawls at less than 6 miles per hour (on the streets) or goes 50 miles an hour up the avenues!

The lights are timed so that you get through dozens of them at a shot - then stop - then go again.

This function would need to be called whenever speed changed from +6 to <6 miles per hour - so that the portion of travel just digested is charged - that's the way the meters work in real life.