Worked Solution: Booking System

1) Print a friendly welcome + what inputs are allowed
2) Ask for dog_name and dog_breed
3) Ask for dog_age (and re-ask if it’s not a sensible number)
4) Ask for dog_size (and re-ask until it is small/medium/large)
5) Use a for loop to print the service menu neatly (Option 1)
6) Ask for service (and re-ask until it is bath/haircut/full)
7) Calculate base_cost using service + dog_size (if/elif/else)
8) Set total_cost = base_cost
9) If dog_age < 1, apply the 10% discount (otherwise: no change)
10) If dog_age ≥ 10, add the $5 senior fee (otherwise: no change)
11) Print a clean booking summary that feels like a confirmation
12) Use a for loop to print summary lines neatly (Option 2)
      

# ------------------------------------------
# Pet Service Booking System
# ------------------------------------------
# This program collects dog information,
# calculates grooming cost based on size and service,
# applies age-based modifiers,
# and prints a clear booking summary.
# ------------------------------------------

# ---- Chunk A: Welcome and Instructions ----

print("Welcome to the Dog Grooming Booking System.")
print("This program is for DOGS only.")
print("Size categories: small (0–10kg), medium (10–25kg), large (25kg+).")
print("Services available: bath, haircut, full.")
print("--------------------------------------------")


# ---- Chunk B: Collect Basic Inputs ----

dog_name = input("Enter your dog's name: ")
dog_breed = input("Enter your dog's breed: ")


# ---- Chunk C: Validate Age Input Using a While Loop ----
# We keep asking until the user gives a sensible number.

while True:
    dog_age_input = input("Enter your dog's age in years: ")

    # Check if the input is a number
    if dog_age_input.isdigit():
        dog_age = int(dog_age_input)

        # Age cannot be negative
        if dog_age >= 0:
            break
        else:
            print("Age cannot be negative. Try again.")
    else:
        print("Please enter a valid whole number for age.")


# ---- Validate Dog Size ----
# This while loop ensures size is one of the allowed options.

valid_sizes = ["small", "medium", "large"]

while True:
    dog_size = input("Enter dog size (small / medium / large): ").lower()

    if dog_size in valid_sizes:
        break
    else:
        print("Invalid size. Please type small, medium, or large.")


# ---- Display Services Using a For Loop ----
# Instead of writing 3 separate print statements,
# we loop through a list.

services = ["bath", "haircut", "full"]

print("\nAvailable services:")
for service_option in services:
    print("-", service_option)


# ---- Validate Service Choice ----

while True:
    service = input("Choose a service: ").lower()

    if service in services:
        break
    else:
        print("Invalid service. Please choose from the list above.")


# ---- Chunk D: Calculate Base Cost ----
# Base cost depends on BOTH service and size.

if service == "bath":
    if dog_size == "small":
        base_cost = 20
    elif dog_size == "medium":
        base_cost = 25
    else:
        base_cost = 30

elif service == "haircut":
    if dog_size == "small":
        base_cost = 30
    elif dog_size == "medium":
        base_cost = 35
    else:
        base_cost = 40

else:  # full grooming
    if dog_size == "small":
        base_cost = 45
    elif dog_size == "medium":
        base_cost = 50
    else:
        base_cost = 60


# ---- Chunk E: Apply Age Modifiers ----

total_cost = base_cost  # Start with base cost

# Puppy discount
if dog_age < 1:
    total_cost = total_cost * 0.9  # Reduce by 10%

# Senior dog fee
if dog_age >= 10:
    total_cost = total_cost + 5


# ---- Chunk F: Output Booking Summary ----
# We store summary lines in a list and print them using a for loop.

summary_lines = [
    "\n----- Booking Summary -----",
    f"Dog name: {dog_name}",
    f"Breed: {dog_breed}",
    f"Age: {dog_age} years",
    f"Size category: {dog_size}",
    f"Service selected: {service}",
    f"Base cost: ${base_cost:.2f}",
    f"Final total cost: ${total_cost:.2f}"
]

for line in summary_lines:
    print(line)

print("----------------------------")

• Can you explain why each loop exists?
• Can you explain why we calculate base_cost before applying modifiers?
• If I removed the decision tree, would you still understand the logic?