15-112 Fall 2012 Optional Quiz B, Part 2 (non-autograded)

* 20 Minutes.  No calculators, no notes, no books, no computers.
* 50 pts [5/5=50,  4/5=45, 3/5=35, 2/5=25, 1/5=15, 0/5=0]

What will the following print?

def f1(a):
    b = [ ]
    for v in a:
        x = a[v%len(a)]
        if (x < v):
            b += [(v,x)]
        elif (x == v):
            b.append("x=" + str(x))
    return b
print f1([6,5,4,3])


def f2(a,b,c):
    (d,e) = (c, b+[])
    f = e + e
    d[0] = 2
    e[0] = 3
    e.append(4)
    f[1] = 5
    print a, b, c, d, e, f
a = [1]
(b,c) = (a,[1])
f2(a,b,c)


def f3():
    x = 0
    while True:
        a = [int(i) for i in ([str(x)*x]*x)]
        if (sum(a) > 1000):
            return x
        x += 1
print f3()
 

For each of the following functions, find values of the parameters so that the functions will return True.

def f4(a):
    assert((type(a) == list) and (a[0] == len(a) == 4))
    for x in a: assert((type(x) == int) and (100 > x > 0))
    s = "".join([str(x) for x in a])
    return ((len(s) == 6) and
            ([i%min(a) for i in a] == range(4)) and
            (a[1] > 10) and
            (int(s[0:2]) == a[3]))


import string
def f5(n):
    # hint: ord("A") == 65, ord("a") == 97, ord("!") == 33
    assert(1000 > n > 0)
    p = ord('a')
    for c in string.ascii_lowercase:
        for d in str(ord(c)): p *= int(d)
        if (p < ord('a')):
            return (n == ord(c))
    return False

Bonus / 5 pts:  What will the following print?

def fbonus(s,b):
    # hint: ord("A") == 65, ord("a") == 97, ord("!") == 33
    if (b): s = s.lower()
    t = sorted([ord(c) for c in list(s) if c.isalpha()])
    t = [t[0]] + [t[i] for i in xrange(1,len(t)) if (t[i] != t[i-1])]
    mc = chr(t[len(t)/2])
    return "".join([c for c in s if ((c.isalpha()) and (c < mc))])
print fbonus("aceD FAB!",False)
print fbonus("acED FAB!",True)