task123-2019-03-17.py

import math

# Gets user input.
# Returns length, width, height and weight.
# The values are NOT validated.
def collect_input():
  l = float(input("Enter length (cm): "))
  w = float(input("Enter width  (cm): "))
  h = float(input("Enter height (cm): "))
  weight = float(input("Enter weight (kg): "))
  return (l,w,h,weight)

# Pass in: length, width, height, weight
# The function returns True if the values are valid and False otherwise.
# If any values are invalid, an error message is printed.
# There may be multiple messages printed.
def validate(l, w, h, weight):
  # Find out if values are valid and print relevant error messages.
  valid = True
  if l <= 0 or w <= 0 or h <= 0 or weight <= 0:
    print("All dimensions must be positive")
    valid = False
  if l > 80 or w > 80 or h > 80:
    print("Length, width, height must be no more than 80cm")
    valid = False
  if l + w + h > 200:
    print("Sum of dimensions must not exceed 200cm")
    valid = False
  if weight < 1.0:
    print("Underweight")
    valid = False
  if weight > 10.0:
    print("Overweight")
    valid = False
  return valid

# Calculates the cost of a parcel based on its weight.
# Up to 5kg is a flat $4.00.
# After that the customer is charged $0.10 for every extra 100g.
def cost_of_parcel(weight):
  # We assume the weight is valid.
  if weight <= 5:
    return 4.00
  else:
    extra_weight = weight - 5
    number_of_hundred_grams = math.ceil(extra_weight * 10)
    return 4.00 + (0.10 * number_of_hundred_grams)

def run():
  n = int(input("How many parcels? "))
  num_valid   = 0
  num_invalid = 0
  total_cost  = 0

  for i in range(1,n+1):
    print("")
    print("Input details for parcel number", i)

    l, w, h, weight = collect_input()
    valid = validate(l, w, h, weight)
    
    if valid == True:
      num_valid  = num_valid + 1
      cost       = cost_of_parcel(weight)
      total_cost = total_cost + cost
      print("Parcel is valid")
      print("Cost of parcel: $", cost)
    else:
      print("Parcel is invalid for the above reason(s)")
      num_invalid = num_invalid + 1

  # Task 2: print report on #valid and #invalid

  print("")
  print("Number of valid parcels:  ", num_valid)
  print("Number of invalid parcels:", num_invalid)

  # Task 3: print the total cost
  print("")
  print("The total cost of the parcels is: $" + str(total_cost))