Valet Parking

Running the program on a bare Ubuntu 16.04 VM

1. Install Go

sudo apt-get update
sudo apt-get -y upgrade
wget https://dl.google.com/go/go1.16.4.linux-amd64.tar.gz
sudo tar -xvf go1.16.4.linux-amd64.tar.gz
sudo mv go /usr/local

2. Setup Go Env

export GOROOT=/usr/local/go
export PATH=$GOROOT/bin:$PATH

3. Clone Project

git clone https://github.com/sudaraka94/valet-parking.git
cd valet-parking

4. Run Tests

go test ./...

5. Run the program

go build -o .
./main

7. Run the program with a custom data file

./main -data=<path to datafile>

Running with docker

1. Clone the repository

git clone https://github.com/sudaraka94/valet-parking.git
cd valet-parking

2. OPTIONAL : Replace the datafile inside project directory with the desired datafile
3. Build docker image

docker build --tag valet-parking .

4. Run on docker

docker run -it valet-parking

Design Decisions

• You can find all the utility methods inside util.go file
• I tried to minimize the usage of third party libraries and do most of the implementations myself

Algorithm

Here is the basic algorithm used in this program. We can separate out the algorithm into four sections,

1. Adding a new vehicle to the park - Overall time complexity : O(n)

• Look for an available slot with the least slot number - Time Complexity: O(n)
• Mark the slot as occupied - Time Complexity: O(1)
• Keep reference of the slot in a hashmap with the vehicle registration number - Time Complexity: O(1)

2. Removing a vehicle from the park - Overall time complexity : O(1)

• Lookup the vehicle in the hashmap using the vehicle registration number - Time Complexity: O(1)
• Remove the vehicle from the hashmap and mark the slot available - Time Complexity: O(1)
• Calculate the fare - Time Complexity: O(1)

Logger implementation

Throughout the whole project, Logger is exposed through an interface. Currently logger interface is implemented by cliLogger, which directly writes to the std out. But in case we need to writeout the results to a file, we can easily do so by introducing a Logger implementation which writes to a file. Logger type can be made configurable via config.yml

logger_config:
  logger_type: "cli" #allowed logger types: cli

Configurability

In this application, supported types of vehicles are configurable. On the application start, it fetches configurations from confi.yml and adjusts accordingly. For an example, if we need to add a third vehicle type we just have to define the vehicle type in the config.yml.

eg:

vehicle_types:
  - name: car
    price_per_hour: 2 #pricePerHour in USD
  - name: motorcycle
    price_per_hour: 1 #pricePerHour in USD
  - name: van
    price_per_hour: 3 #pricePerHour in USD