How to Think, Plan and Code in Python

try:
   age = int(input("Enter your age: "))
   if age < 0:
       print("Invalid age! Age cannot be negative.")
   elif age <= 12:
       print("You are a child.")
   elif age <= 19:
       print("You are a teenager.")
   elif age <= 59:
       print("You are an adult.")
   else:
       print("You are a senior.")
except ValueError:
   print("Please enter a valid number.")

try:
   score1 = float(input("Enter first test score: "))
   score2 = float(input("Enter second test score: "))
   score3 = float(input("Enter third test score: "))
   
   if 0 <= score1 <= 100 and 0 <= score2 <= 100 and 0 <= score3 <= 100:
       average = (score1 + score2 + score3) / 3
       
       if average >= 90:
           grade = "A"
       elif average >= 80:
           grade = "B"
       elif average >= 70:
           grade = "C"
       elif average >= 60:
           grade = "D"
       else:
           grade = "F"
       
       print(f"Average: {average:.1f}, Grade: {grade}")
   else:
       print("All scores must be between 0 and 100.")
except ValueError:
   print("Please enter valid numbers for all scores.")

password = input("Enter your password: ")
special_chars = "!@#$%^&*()_+-=[]{}|;:,.<>?"

# Check all requirements
has_length = len(password) >= 8
has_upper = any(c.isupper() for c in password)
has_lower = any(c.islower() for c in password)
has_digit = any(c.isdigit() for c in password)
has_special = any(c in special_chars for c in password)

if has_length and has_upper and has_lower and has_digit and has_special:
   print("Strong password! ✓")
else:
   print("Weak password. Missing:")
   if not has_length: print("  - At least 8 characters")
   if not has_upper: print("  - Uppercase letter")
   if not has_lower: print("  - Lowercase letter")
   if not has_digit: print("  - Number")
   if not has_special: print("  - Special character")

tasks = []

def display_menu():
   print("\n📝 To-Do List Manager")
   print("1. Add task")
   print("2. Mark task complete")
   print("3. View all tasks")
   print("4. Exit")

while True:
   display_menu()
   choice = input("Choose an option: ")
   
   if choice == '1':
       task = input("Enter new task: ")
       tasks.append({'task': task, 'completed': False})
       print(f"✓ Added: {task}")
   
   elif choice == '2':
       if tasks:
           for i, task_dict in enumerate(tasks, 1):
               status = "✓" if task_dict['completed'] else "○"
               print(f"  {i}. {status} {task_dict['task']}")
           
           try:
               task_num = int(input("Enter task number to complete: ")) - 1
               tasks[task_num]['completed'] = True
               print("✓ Task marked as complete!")
           except (IndexError, ValueError):
               print("Invalid task number!")
       else:
           print("No tasks available!")
   
   elif choice == '3':
       if tasks:
           print("\n📋 All Tasks:")
           for i, task_dict in enumerate(tasks, 1):
               status = "✓" if task_dict['completed'] else "○"
               print(f"  {i}. {status} {task_dict['task']}")
       else:
           print("No tasks yet!")
   
   elif choice == '4':
       print("👋 Goodbye!")
       break
   
   else:
       print("Invalid option! Please try again.")

def celsius_to_fahrenheit(celsius):
   return (celsius * 9 / 5) + 32

def celsius_to_kelvin(celsius):
   return celsius + 273.15

def fahrenheit_to_celsius(fahrenheit):
   return (fahrenheit - 32) * 5 / 9

print("🌡️  Temperature Converter")
print("1. Celsius to Fahrenheit & Kelvin")
print("2. Fahrenheit to Celsius & Kelvin")
print("3. Kelvin to Celsius & Fahrenheit")

try:
   choice = int(input("Choose conversion type: "))
   temperature = float(input("Enter temperature: "))
   
   if choice == 1:
       if temperature < -273.15:
           print("Error: Temperature below absolute zero!")
       else:
           fahrenheit = celsius_to_fahrenheit(temperature)
           kelvin = celsius_to_kelvin(temperature)
           print(f"{temperature}°C = {fahrenheit:.1f}°F = {kelvin:.1f}K")
   
   elif choice == 2:
       if temperature < -459.67:
           print("Error: Temperature below absolute zero!")
       else:
           celsius = fahrenheit_to_celsius(temperature)
           kelvin = celsius_to_kelvin(celsius)
           print(f"{temperature}°F = {celsius:.1f}°C = {kelvin:.1f}K")
   
   elif choice == 3:
       if temperature < 0:
           print("Error: Kelvin cannot be negative!")
       else:
           celsius = temperature - 273.15
           fahrenheit = celsius_to_fahrenheit(celsius)
           print(f"{temperature}K = {celsius:.1f}°C = {fahrenheit:.1f}°F")
   
   else:
       print("Invalid choice!")

except ValueError:
   print("Please enter valid numbers!")

text = input("Enter some text to analyze: ")

# Basic counts
char_count = len(text)
char_no_spaces = len(text.replace(' ', ''))
words = text.split()
word_count = len(words)

# Sentence count (rough estimate)
sentence_endings = ['.', '!', '?']
sentence_count = sum(text.count(ending) for ending in sentence_endings)

# Find longest word
if words:
   longest_word = max(words, key=len)
   avg_word_length = sum(len(word) for word in words) / word_count
else:
   longest_word = "None"
   avg_word_length = 0

# Vowel and consonant count
vowels = "aeiouAEIOU"
vowel_count = sum(1 for char in text if char in vowels)
consonant_count = sum(1 for char in text if char.isalpha() and char not in vowels)

# Display results
print("\n📊 Text Analysis Results:")
print("=" * 30)
print(f"Total characters: {char_count}")
print(f"Characters (no spaces): {char_no_spaces}")
print(f"Word count: {word_count}")
print(f"Estimated sentences: {sentence_count}")
print(f"Longest word: '{longest_word}' ({len(longest_word)} chars)")
print(f"Average word length: {avg_word_length:.1f}")
print(f"Vowels: {vowel_count}, Consonants: {consonant_count}")

balance = 1000.00  # Starting balance
transactions = []

def add_transaction(transaction_type, amount):
   import datetime
   timestamp = datetime.datetime.now().strftime("%Y-%m-%d %H:%M")
   transactions.append({
       'type': transaction_type,
       'amount': amount,
       'timestamp': timestamp,
       'balance_after': balance
   })

print("🏦 Welcome to Simple Bank!")

while True:
   print("\n1. Check Balance")
   print("2. Deposit Money")
   print("3. Withdraw Money")
   print("4. Transaction History")
   print("5. Exit")
   
   choice = input("Choose an option: ")
   
   if choice == '1':
       print(f"💰 Current Balance: ${balance:.2f}")
   
   elif choice == '2':
       try:
           amount = float(input("Enter deposit amount: $"))
           if amount > 0:
               balance += amount
               add_transaction("Deposit", amount)
               print(f"✅ Deposited ${amount:.2f}. New balance: ${balance:.2f}")
           else:
               print("⚠️  Deposit amount must be positive!")
       except ValueError:
           print("Invalid amount!")
   
   elif choice == '3':
       try:
           amount = float(input("Enter withdrawal amount: $"))
           if amount > 0:
               if amount <= balance:
                   balance -= amount
                   add_transaction("Withdrawal", amount)
                   print(f"✅ Withdrew ${amount:.2f}. New balance: ${balance:.2f}")
               else:
                   print("❌ Insufficient funds!")
           else:
               print("⚠️  Withdrawal amount must be positive!")
       except ValueError:
           print("Invalid amount!")
   
   elif choice == '4':
       if transactions:
           print("\n📋 Transaction History:")
           for transaction in transactions[-10:]:  # Last 10 transactions
               print(f"  {transaction['timestamp']} | {transaction['type']}: ${transaction['amount']:.2f} | Balance: ${transaction['balance_after']:.2f}")
       else:
           print("No transactions yet!")
   
   elif choice == '5':
       print("👋 Thank you for banking with us!")
       break
   
   else:
       print("Invalid option!")