solution.py

def hello_world():
    '''Prints "Hello World!".'''
    print("Hello World!")
    return


def sum(a, b):
    '''Accepts 2 numbers as parameters, returns sum of a and b.'''
    return a + b


def sub(a, b):
    '''Accepts 2 numbers as parameters, returns subtraction of a and b.'''
    return a - b


def product(a, b):
    '''Accepts 2 numbers as parameters, returns product of a and b.'''
    # CHALLENGE: use a for loop and your sum function to implement product
    ans = 0
    for i in range(b):
        ans = sum(ans, a)
    return ans


def divide(a, b):
    '''Accepts 2 numbers as parameters, returns a divided by b.'''
    # only pass in numbers that are divisible for sake of implementation
    # CHALLENGE: use a while loop and your sub function to implement divide
    ans = 0
    while a > 0:
        a = sub(a, b)
        ans += 1
    return ans


def root(num):
    '''Accepts a number as a parameter, returns the sqrt of num.'''
    # only pass in numbers that are perfect squares for sake of implementation
    # leetcode easy
    # CHALLENGE: do not use any built-in Python functions

    # Basic approach, look up binary search approach if interested
    # base cases
    if num is 0 or num is 1:
        return num
        
    # Try all numbers until i*i equal to num.
    i = 1
    result = 1
    while result < num:
        i += 1
        result = i * i
      
    return i


def main():
    '''The main function is where you will test all of your functions.'''
    hello_world()
    print("Testing sum:")
    print("EXPECTED: %d, ACTUAL: %d\n" % (5, sum(2, 3)))
    print("Testing sub:")
    print("EXPECTED: %d, ACTUAL: %d\n" % (5, sub(7, 2)))
    print("Testing product:")
    print("EXPECTED: %d, ACTUAL: %d\n" % (10, product(2, 5)))
    print("Testing divide:")
    print("EXPECTED: %d, ACTUAL: %d\n" % (5, divide(10, 2)))
    print("Testing root:")
    print("EXPECTED: %d, ACTUAL: %d\n" % (5, root(25)))
    # Add any additional test cases if needed

if __name__ == "__main__":
    main()