Capstone Project: Ticket to Mars

Description

Lately I’ve been reading the book Get Programming with Go by Nathan Youngman and Roger Peppé (2018). It’s a well structured book with well thought through exercises and capstone projects sprinkled throughout. In order to advance my knowledge of go, I thought I’d do all the exercises in the book and make a post about each of the capstone projects and offer my take on how I solved them; an equal parts explorative and learning endeavour. The “Ticket to Mars” project is the first capstone project and thus closes off unit one of the book, which covers loops & branches, variable scope, basic logic, control flow and short declaration of variables among other things.

Task

Create a ticket generator for space trips to Mars. Conditions:

• The speed at which the ship will travel is assigned randomly
• Round-trips cost twice as much
• Faster trips are more expensive
• Distance to Mars at departure time: 62,100,000 km

For a full description of the project, see Get Programming with Go (Youngman, Peppé, 2018).

Method

I tried to limit myself to the topics that have been covered in the book while solving this exercise. This can result in some rather redundant and nonsensical code. For this exercise the tricky part was to figure out how to produce the table if no lists, arrays, matrices or dataframes are allowed. The next step was to figure out what part of the code to loop through when using this sort of pseudo-table. All-in-all the project was straight forward and the tricky bits arose due to more conventional methods being off limits.

Output

Spaceline       Days  Trip type  Price 
======================================
Virgin Galactic   44  Round-trip $  72 
Space Adventures  34  One-way    $  38 
Space Adventures  44  Round-trip $  72 
Virgin Galactic   26  Round-trip $  82 
Space Adventures  35  Round-trip $  76 
Space Adventures  26  Round-trip $  82 
Virgin Galactic   31  One-way    $  39 
Virgin Galactic   23  One-way    $  43 
Space Adventures  25  One-way    $  42 
Space Adventures  32  One-way    $  39

Code

package __CapstoneMars

import (
  "fmt"
  "math/rand"
)

const MarsDistance int = 62100000

func TicketPricing() {
  var Spaceline string
  var TripType string

  fmt.Printf("\n%-15v %-5v %v %6v \n", "Spaceline", "Days", "Trip type", "Price")
  fmt.Println("======================================")

  for count := 10; count > 0; count-- {

    Speed := rand.Intn(15) + 16
    Price := 28 + (Speed / 2)

    Days := MarsDistance / Speed / 60 / 60 / 24

    switch pseudoseed := rand.Intn(3) + 1; pseudoseed {
    case 1:
      Spaceline = "Virgin Galactic "
    case 2:
      Spaceline = "SpaceX          "
    case 3:
      Spaceline = "Space Adventures"
    }

    switch pseudoseed := rand.Intn(2) + 1; pseudoseed {
    case 1:
      TripType = "One-way   "
    case 2:
      TripType = "Round-trip"
      Price = 2 * Price
    }

    fmt.Printf("%v %3v %11v $ %3v \n", Spaceline, Days, TripType, Price)
  }
}

References

Youngman, Nathan & Peppé, Roger. (2018). Get programming with go. Manning Publications.