15-110 PS3 Sample Solutions - Spring 2018

1. 
(a) CIRCLE(2,2,2)
    CIRCLE(2,6,2)
    CIRCLE(4,4,2)
    CIRCLE(4,4,3)
    CIRCLE(6,2,2)
    CIRCLE(6,6,2)

(b) SQUARE(0,8,4)
    SQUARE(1,8,3)
    SQUARE(1,7,3)
    SQUARE(4,4,4)
    SQUARE(4,4,3)
    SQUARE(5,3,3)

2.
(a) x     y     temp   p     q
    60    105   -      6300  -
    105   60    105    6300  60
    60    45    60     6300  105
    45    15    45     6300  140
    15    0     15     6300  420

(b) lcm2(60,105,0)
    --> lcm2(60,105,105)
    --> lcm2(60,105,210)
    --> lcm2(60,105,315)
    --> lcm2(60,105,420) --> 420

3.
(a) 
def compute_sum(numlist):
    total = 0
    i = 0
    while i < len(numlist):
        total = total + numlist[i]
        i = i + 1
    return total

(b) 
def compute_sum(numlist):
    total = 0
    for item in numlist:
        total = total + item
    return total

4. 
(a) Change line 20 to: return len(primelist)
(b) Change line 20 to: return primelist[-1]  (or primelist[len(primelist)-1])
(c) The result is [4,8,12,16]. If an element is removed, the subsequent 
    values shift over so there is a new value in this same position 
    to be checked, but the for loop moves on.
(d) Change line 20 to: return primelist + numlist