CS101 Final Exam

科目名稱：計算機概論	期末考	開課系所：資工系		考試日期	2018.1.18
系所別：	年級：	學號：	姓名：	考試時間	08:20-10:00

Open book; turn off computer & mobile phone

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(10%) Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

# Shuffle
def main():
    aList = ["Alpha", "Bravo", "Charlie", "Delta", "Echo",
             "Foxtrot", "Golf", "Hotel", "India", "Juliet",
             "Kilo", "Lima", "Mike", "November", "Oscar",
             "Papa", "Quebec", "Romeo", "Sierra", "Tango",
             "Uniform", "Victor", "Whiskey", "Xray", "Yankee",
             "Zulu"]
    bList = shuffle(aList)
    print(bList[:8])

def shuffle(a):
    N = len(a)
    result = [" "] * N
    for i in range(N):
        k = i * 7 % N
        result[k] = a[i]
    return result

main()
(10%) Determine whether the following code has syntax errors or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

# String concatenation
def f(x):
    temp=''
    for c in x:
        temp = c + temp + c
    return temp

def main():
    words = ['MALAYSIA', 'TRULY', 'ASIA']
    for x in words:
        print( f(x) )

main()
(10%) What will be the output of the following program?

# Return Value of a Function
def star(n):
print( '*' * n )
return n

print( star(10) )
print( star(5) , star(5) )
(10%) What will be the output of the following program?

# Definite Loop
for i in range(1,6):
    for j in range(1, i+1):
        print(j, end='')
    print()
(10%) What will be the output of the following program?

# import a module
names = ["alice", "bob", "charlie"]
for x in names:
    fname = x + ".py"
    outfile = open(fname, "w")
    print('def walk():\n    print("'+x+' walks")', file=outfile)
    print('def smile():\n   print("'+x+' smiles")', file=outfile)
    print('def sing():\n    print("'+x+' sings")', file=outfile)
    outfile.close()

from alice import smile
from bob import walk
from charlie import sing
smile()
walk()
sing()
(10%) What will be the output of the following program?

# while
def f(s, c):
    positions = []
    n = s.find(c)
    while n >=0:
        positions.append(n)
        n = s.find(c, n+1)
    return positions

def main():
    title = "A SONG OF ICE AND FIRE"
    for c in f(title, ' '):
        print(c, end=' ')
    print()

main()
(10%) Determine whether the following code has syntax erros or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

# Transposition Cipher
def main():
    key, msg = getInputs()
    plaintext = encrypt(msg, key)
    print(plaintext)

def getInputs():
    message = "C:eETSShmaHeroOtmfTFuhureteIeCsrCHeC"
    key = 3
    return key, message

def encrypt(msg, N):
    from math import ceil
    s = ''
    for i in range(0, len(msg), N*N):
        s = s + transpose(msg[i:i+N*N], N)
    return s

def transpose(msg, N):
    t = []
    for i in range(N):
    # t = [ ['A'] * N ] * N
        t.append( [chr(65+i)] * N )
    p = 0
    for i in range(N):
        for j in range(N):
            if p < len(msg):
                t[i][j] = msg[p]
            p = p + 1
    s = ''
    for j in range(N):
        for i in range(N):
            s = s + t[i][j]
    return s

main()

(10%) Determine whether the following code has syntax erros or
    not.  If it is correct, predict its output.  If it is
    incorrect, point out the
    mistake(s).

# Define a Class
def gcd(a, b):
    while b != 0:
       a, b = b, a % b
    return a

class Rational:
    def __init__(self, n=0, d=1):
        self.numerator = n
        self.denominator = d
    def reduce(self):
        d = gcd(self.numerator, self.denominator)
        self.numerator = self.numerator // d
        self.denominator = self.denominator // d
    def __str__(self):
        self.reduce()
        if self.denominator == 1:
            result = str(self.numerator)
        else:
            result = str(self.numerator)+'/'+str(self.denominator)
        return result

def main():
    a = Rational(36)
    b = Rational(24, 1)
    c = Rational(36, 24)
    qList = [a, b, c]
    for q in qList:
        print(q)

main()

(10%) Determine whether the following code has syntax erros or
    not.  If it is correct, predict its output.  If it is
    incorrect, point out the
    mistake(s).

# Method of an Object
def gcd(a, b):
    while b != 0:
       a, b = b, a % b
    return a

class Rational:
    def __init__(self, n=0, d=1):
        self.numerator = n
        self.denominator = d
    def reduce(self):
        d = gcd(self.numerator, self.denominator)
        self.numerator = self.numerator // d
        self.denominator = self.denominator // d
    def __str__(self):
        self.reduce()
        if self.denominator == 1:
            result = str(self.numerator)
        else:
            result = str(self.numerator)+'/'+str(self.denominator)
        return result
    def add(self, q):
        n = self.numerator * q.denominator + self.denominator * q.numerator
        d = self.denominator * q.denominator
        return Rational(n, d)

def main():
    c = Rational(36, 24)
    d = Rational(24, 36)
    e = c.add(d)
    qList = [c, d, e]
    for q in qList:
        print(q)

main()

(10%) Determine whether the following code has syntax erros or not. If it is correct, predict its output. If it is incorrect, point out the mistake(s).

# Sorting a List of Objects
def gcd(a, b):
    while b != 0:
       a, b = b, a % b
    return a

class Rational:
    def __init__(self, n=0, d=1):
        self.numerator = n
        self.denominator = d
    def reduce(self):
        d = gcd(self.numerator, self.denominator)
        self.numerator = self.numerator // d
        self.denominator = self.denominator // d
    def __str__(self):
        self.reduce()
        if self.denominator == 1:
            result = str(self.numerator)
        else:
            result = str(self.numerator)+'/'+str(self.denominator)
        return result
    def add(self, q):
        n = self.numerator * q.denominator + self.denominator * q.numerator
        d = self.denominator * q.denominator
        return Rational(n, d)

def reciprocal(q):
    return q.denominator / q.numerator

def main():
    c = Rational(36, 24)
    d = Rational(24, 36)
    e = c.add(d)
    qList = [c, d, e]
    qList.sort(key=reciprocal)
    for q in qList:
        print(q)

main()