while_loops.py

"""
While Loop Exercises - Complete the functions below
Run this file with: python topic.py
Or work interactively with: python3 -i topic.py
"""

# Exercise 1: Basic While Loops
def count_down(n):
    """Print countdown from n to 1, then print 'Blast off!'"""
    # Your code here
    pass

def sum_while_positive(numbers):
    """Sum numbers from the list while they are positive. Stop at first non-positive."""
    # Your code here
    pass

def find_first_even(numbers):
    """Return the first even number in the list, or None if no even number exists."""
    # Your code here
    pass

# Exercise 2: Input Validation Loops
def get_positive_number():
    """Keep asking user for input until they enter a positive number."""
    # Your code here - use input() function
    # Note: This won't work in automated testing, so just return a placeholder
    return 5  # placeholder for testing

def get_valid_grade():
    """Keep asking for a grade between 0 and 100."""
    # Your code here - return placeholder for testing
    return 85  # placeholder for testing

def get_yes_or_no():
    """Keep asking until user enters 'yes' or 'no'."""
    # Your code here - return placeholder for testing
    return "yes"  # placeholder for testing

# Exercise 3: Number Processing
def factorial_while(n):
    """Calculate factorial using while loop."""
    # Your code here
    pass

def fibonacci_sequence(limit):
    """Generate Fibonacci sequence up to limit."""
    # Your code here
    pass

def digital_root(number):
    """Keep summing digits until single digit remains."""
    # Example: 9875 -> 9+8+7+5 = 29 -> 2+9 = 11 -> 1+1 = 2
    # Your code here
    pass

# Exercise 4: String Processing
def remove_vowels_while(text):
    """Remove all vowels from text using while loop."""
    # Your code here
    pass

def reverse_string_while(text):
    """Reverse string using while loop."""
    # Your code here
    pass

def find_longest_word(text):
    """Find the longest word in a sentence."""
    # Your code here
    pass

# Exercise 5: List Processing
def remove_duplicates_while(items):
    """Remove duplicates from list while preserving order."""
    # Your code here
    pass

def merge_sorted_arrays(arr1, arr2):
    """Merge two sorted arrays into one sorted array."""
    # Your code here
    pass

def find_peak_element(numbers):
    """Find an element that is greater than its neighbors."""
    # Your code here
    pass

# Exercise 6: Game Logic
def guessing_game_logic(secret, max_attempts):
    """Simulate number guessing game logic."""
    # Return number of attempts needed (simulate with simple logic)
    # Your code here
    pass

def rock_paper_scissors_tournament(rounds):
    """Simulate tournament and return winner."""
    # Your code here - return placeholder
    return "Player 1"  # placeholder

def dice_roll_until_sum(target_sum):
    """Keep rolling two dice until their sum equals target."""
    # Your code here - return number of rolls needed
    # Use random.randint(1, 6) for dice rolls
    import random
    # Your code here
    pass

# Exercise 7: Mathematical Algorithms
def gcd_while(a, b):
    """Calculate Greatest Common Divisor using Euclidean algorithm."""
    # Your code here
    pass

def power_while(base, exponent):
    """Calculate base^exponent using while loop."""
    # Your code here
    pass

def is_prime_while(number):
    """Check if number is prime using while loop."""
    # Your code here
    pass

# Exercise 8: Advanced Processing
def collatz_sequence_length(n):
    """Calculate length of Collatz sequence starting from n."""
    # Collatz: if even, divide by 2; if odd, multiply by 3 and add 1
    # Continue until reaching 1
    # Your code here
    pass

def binary_search_while(sorted_list, target):
    """Implement binary search using while loop."""
    # Your code here
    pass

def find_equilibrium_index(numbers):
    """Find index where sum of left elements equals sum of right elements."""
    # Your code here
    pass

def run_tests():
    """Test all the functions to verify they work correctly."""
    print("Testing Basic While Loops:")
    print("count_down(5):")
    count_down(5)  # Should print 5, 4, 3, 2, 1, Blast off!
    
    print(f"sum_while_positive([2, 3, 4, -1, 5]): {sum_while_positive([2, 3, 4, -1, 5])}")  # Should print 9
    print(f"find_first_even([1, 3, 4, 7]): {find_first_even([1, 3, 4, 7])}")  # Should print 4
    print(f"find_first_even([1, 3, 5]): {find_first_even([1, 3, 5])}")  # Should print None

    print("\nTesting Number Processing:")
    print(f"factorial_while(5): {factorial_while(5)}")  # Should print 120
    print(f"fibonacci_sequence(20): {fibonacci_sequence(20)}")  # Should print [0, 1, 1, 2, 3, 5, 8, 13]
    print(f"digital_root(9875): {digital_root(9875)}")  # Should print 2

    print("\nTesting String Processing:")
    print(f"remove_vowels_while('hello world'): {remove_vowels_while('hello world')}")  # Should print 'hll wrld'
    print(f"reverse_string_while('hello'): {reverse_string_while('hello')}")  # Should print 'olleh'
    print(f"find_longest_word('The quick brown fox'): {find_longest_word('The quick brown fox')}")  # Should print 'quick' or 'brown'

    print("\nTesting List Processing:")
    print(f"remove_duplicates_while([1, 2, 2, 3, 1]): {remove_duplicates_while([1, 2, 2, 3, 1])}")  # Should print [1, 2, 3]
    print(f"merge_sorted_arrays([1, 3, 5], [2, 4, 6]): {merge_sorted_arrays([1, 3, 5], [2, 4, 6])}")  # Should print [1, 2, 3, 4, 5, 6]
    print(f"find_peak_element([1, 3, 2, 4, 1]): {find_peak_element([1, 3, 2, 4, 1])}")  # Should print index of peak

    print("\nTesting Mathematical Algorithms:")
    print(f"gcd_while(48, 18): {gcd_while(48, 18)}")  # Should print 6
    print(f"power_while(2, 8): {power_while(2, 8)}")  # Should print 256
    print(f"is_prime_while(17): {is_prime_while(17)}")  # Should print True
    print(f"is_prime_while(15): {is_prime_while(15)}")  # Should print False

    print("\nTesting Advanced Processing:")
    print(f"collatz_sequence_length(5): {collatz_sequence_length(5)}")  # Should print length of sequence
    print(f"binary_search_while([1, 3, 5, 7, 9], 5): {binary_search_while([1, 3, 5, 7, 9], 5)}")  # Should print 2
    print(f"find_equilibrium_index([1, 3, 5, 2, 2]): {find_equilibrium_index([1, 3, 5, 2, 2])}")  # Should find equilibrium

if __name__ == "__main__":
    print("Python While Loop Exercises")
    print("=" * 40)
    print("Complete the functions above, then run this file to test them.")
    print("Uncomment the line below when you're ready to test:")
    print()
    # run_tests()  # Uncomment this line to run tests