1. ./descendSort.py
2. ./fibs2.py
3. ./swap.py
4. ./test.py

# Demonstrate passing lists to functions
# One function modifies the list parameter, 
# one function is a "pure function" and does not modify the parameter
# CSCI111

import test

def main():
    # test descendSort3Nums
    aList = [1,2,3]
    descendSort3Nums(aList)
    print(aList)

    aList = [0, 5, -3]
    descendSort3Nums(aList)
    print(aList)
    
    aList = [7,4,1]
    descendSort3Nums(aList)
    print(aList)
    
    aList = [-1, -1, -3]
    descendSort3Nums(aList)
    print(aList)
    
    aList = [-1, -5, -3]
    descendSort3Nums(aList)
    print(aList)

def descendSort3Nums(list3):
    """
    Parameter: list3: a list containing three numbers
    Sorts the list in descending order
    Note: does not return anything, no output 
    """
    if list3[1] > list3[0]:
        # swap 'em
        tmp = list3[0]
        list3[0] = list3[1]
        list3[1] = tmp

    if list3[2] > list3[1]:
        # swap 'em
        tmp = list3[1]
        list3[1] = list3[2]
        list3[2] = tmp
    
    if list3[1] > list3[0]:
        # swap 'em
        tmp = list3[0]
        list3[0] = list3[1]
        list3[1] = tmp

def createDescendingList(list3):
    """
    Parameter: list3: a list containing three numbers
    Sorts the list in descending order and returns that list
    (Example of "pure function")
    """
    copyOfList3 = list3 + []
    
    if copyOfList3[1] > copyOfList3[0]:
        # swap 'em
        tmp = copyOfList3[0]
        copyOfList3[0] = copyOfList3[1]
        copyOfList3[1] = tmp

    if copyOfList3[2] > copyOfList3[1]:
        # swap 'em
        tmp = copyOfList3[1]
        copyOfList3[1] = copyOfList3[2]
        copyOfList3[2] = tmp
    
    if copyOfList3[1] > copyOfList3[0]:
        # swap 'em
        tmp = copyOfList3[0]
        copyOfList3[0] = copyOfList3[1]
        copyOfList3[1] = tmp
        
    return copyOfList3

def testDescendSort3Nums():
    origList = [1, 2, 3]
    descendSort3Nums(origList)
    # test that the list sorted is in the other order
    test.testEqual( origList, [3, 2, 1])
    
    aList = [-1, -5, -3]
    descendSort3Nums(aList)
    test.testEqual( aList, [-1, -3, -5])

def testCreateDescendingSort3Nums():
    origList = [1, 2, 3]
    test.testEqual( createDescendingList(origList), [3, 2, 1])
    # verify that the original list didn't change.
    test.testEqual( origList, [1, 2, 3] )
    
    aList = [-1, -5, -3]
    test.testEqual( createDescendingList(aList), [-1, -3, -5])
    test.testEqual( aList, [-1, -5, -3])

testDescendSort3Nums()
testCreateDescendingSort3Nums()

#main()

# Example of creating a list of the appropriate size
# Computes the first SIZE Fibonacci numbers
# Tradeoff of using more space (the list, rather than a few variables)
# for easier implementation
# Sara Sprenkle

SIZE = 20

print("This program generates the first", SIZE, "Fibonacci numbers")

# creates a list of size SIZE, containing all 0s
fibs = [0]*SIZE

#fibs[0] = 0
fibs[1] = 1

for x in range(2, len(fibs)):
    newfib = fibs[x-1]+fibs[x-2]
    fibs[x] = newfib

# print that list out, as a list
print(fibs)

# To print out the list, individually (instead of as a list)
print("Printing elements of list: ")
for num in fibs:
    print(num, end=" ")
print()

# Attempt at swapping two variables in a function
# FAIL!  Swapping within a function won't work. :(
# Why?  With immutable data types (like integers), the functions are
# passed *copies* of the parameters, not the original variables

def main():
    x = 5
    y = 7
    
    print("In main:")
    print("x =", x)
    print("y =", y) 
    
    swap(x, y)
    
    print("In main after call to swap:")
    print("x =", x)
    print("y =", y) 


def swap(a, b):
    """
    Swaps the values stored in a and b
    """
    tmp = a
    a = b
    b = tmp
    print("In swap function: ", a, b)

main()

# From How to Think Like a Computer Scientist textbook

def testEqual(actual, expected):
    if type(expected) == type(1):
        # they're integers, so check if exactly the same
        if actual == expected:
            print('Pass')
            return True
    elif type(expected) == type(1.11):
        # a float is expected, so just check if it's very close, to allow for
        # rounding errors
        if abs(actual-expected) < 0.00001:
            print('Pass')
            return True
    else:
        # check if they are equal
        if actual == expected:
            print('Pass')
            return True
    print('Test Failed: expected ' + str(expected) + ' but got ' + str(actual))
    return False