Be-A-Computer: Functions and Lists

The purpose of these problems is to allow you to test your understanding of functions and lists. They should not take more than an hour to complete.

You should do these warm-up exercises by hand. We provide files that will allow you to check your answers.

To get started, run git pull upstream master to make sure you have the latest files. You can check your answers by running the Python program functions-lists.py in pp/bac/

Warm-up exercise #1: What is the output of the following code?

def F1(i, j) :
    print("F1({}, {})".format(i, j))
    F2(j, i+j)
    print("F1: i = {}, j = {}".format(i, j))
    

def F2(i, j) :
    print("    F2({}, {})".format(i, j))
    k = F3(i, j)
    print("    F2: i = {}, j = {}, k = {}".format(i, j, k))
    

def F3(i, j) :
    print("        F3({}, {})".format(i, j))
    i = i+j
    j = i+2*j
    k = 2*i+3*j
    print("        F3: i = {}, j = {}, k = {}".format(i, j, k))
    return k
    

print("Warmup exercise 1:")
F1(1, 1)
print()

Warm-up exercise #2: What is the output of the following code?

def mystery1(l):
    rv = []
    for x in l:
        rv = [x] + rv
    return rv

print("Warmup exercise 2:")
l = [0, 1, 2, 3, 4]
nl = mystery1(l)
print("l: ", l)
print("nl: ", nl)

Warm-up exercise #3: What is the output of the following code?

def mystery2(l):
    rv = []
    for i in range(len(l)-1, -1, -1):
        rv.append(l[i])
    return rv

print("Warmup exercise 3:")
l = [0, 1, 2, 3, 4]
nl = mystery2(l)
print("l: ", l)
print("nl: ", nl)

Challenge exercise: What is the output of the following code?

def mystery3(l):
    n = len(l)
    for i in range(n // 2):
        t = l[i]
        l[i] = l[n-i-1]
        l[n-i-1] = t


print("Challenge exercise:")
l = [0, 1, 2, 3, 4]
mystery3(l)
print("l: ", l)