《Python核心编程》答案 第8章

8-1:

（a）：C, E

（b）：D, E

（c）：B, E

8-2:

#!/usr/bin/env python

print ‘Input three numbers to f, t, i:‘
f = int(raw_input(‘f: ‘))
t = int(raw_input(‘t: ‘))
i = int(raw_input(‘i: ‘))
for item in range(f, t+1, i):
    print item,

8-3:

(a): range(10)

(b): range(3, 19, 3)

(c): range(-20, 861, 220)

8-4:

def isprime(num):
    count = num / 2
    while count > 1:
        if num % count == 0:
            return False
        count -= 1
    if num == 1:
        return False
    return True

8-5:

def getfactors(num):
    ans = []
    for i in range(1, num+1):
        if num % i == 0:
            ans.append(i)
    return ans

8-6:

def isprime(num):
    count = num / 2
    while count > 1:
        if num % count == 0:
            return False
        count -= 1
    if num == 1:
        return False
    return True

def getfactors(num):
    ans = []
    for i in range(1, num+1):
        if num % i == 0:
            ans.append(i)
    return ans

def primeFactorization(num):
    factors = getfactors(num)
    primefactor = [item for item in factors if isprime(item)]
    ans = []
    for i in primefactor:
        while num % i == 0:
            ans.append(i)
            num = num / i
    return ans

8-7:

def getfactors(num):
    ans = []
    for i in range(1, num+1):
        if num % i == 0:
            ans.append(i)
    return ans

def isperfect(num):
    factorsum = sum(getfactors(num)[:-1])
    if factorsum == num:
        return 1
    else:
        return 0

8-8:

def factorial(n):
    ans = 1
    for item in range(1, n+1):
        ans *= item
    return ans

8-9:

def fibonacci(n):    #递归方法
    if n == 1 or n == 2:
        return 1
    return fibonacci(n-2) + fibonacci(n-1)

def fibonacci2(n):    #非递归方法
    a, b = 1, 1
    if n == 1 or n == 2:
        return 1
    for x in range(n-2):
        a, b = b, a + b
    return b

8-10：稍后更新

8-11:

num = int(raw_input(‘Enter total number of names: ‘))
print
names = {}
wrongnum = 0
for item in range(num):
    name = raw_input(‘Please enter name %d: ‘ % item)
    if ‘,‘ not in name:
        wrongnum += 1
        print "Wrong format... should be Last, First"
        print "You have done this %d time(s) already. Fixing input..." % wrongnum
        ln, fn = name.split()
        names[fn] = ln
    else:
        ln, fn = name.split(‘,‘)
        fn = fn.strip()
        names[ln] = fn
print
print "The sorted list (by last name) is:"
for lastname in sorted(names):
    print ‘%s, %s‘ % (lastname, names[lastname])

8-12:

 1 def mybin(num):
 2     ans = ‘‘
 3     while num > 0:
 4         b = str(num % 2)
 5         ans = b + ans
 6         num = num / 2
 7     if len(ans) < 5:
 8         ans = ‘0‘*(5-len(ans)) + ans
 9     return ans
10
11 def myoct(num):
12     ans = ‘‘
13     while num > 0:
14         b = str(num % 8)
15         ans = b + ans
16         num = num / 8
17     return ans
18
19 def myhex(num):
20     ans = ‘‘
21     adict = {0: ‘0‘, 1:‘1‘, 2:‘2‘, 3:‘3‘, 4:‘4‘, 5:‘5‘, 6:‘6‘, 7:‘7‘, 8:‘8‘, 9:‘9‘, 10:‘a‘, 11:‘b‘, 12:‘c‘, 13:‘d‘, 14:‘e‘, 15:‘f‘}
22     while num > 0:
23         b = adict[num % 16]
24         ans = b + ans
25         num = num / 16
26     return ans
27
28 begin = int(raw_input(‘Enter begin value: ‘))
29 end = int(raw_input(‘Enter end value: ‘))
30 if 31 < end < 127:
31     print "%5s\t%5s\t%5s\t%5s\t%5s" % ("DEC", "BIN", "OCT", "HEX", "ACSII")
32     print ‘-‘ * 40
33     for i in range(begin, (end+1)):
34         if i < 32:
35             c = ‘‘
36         else:
37             c = chr(i)
38         print "%5d\t%5s\t%5s\t%5s\t%5s" % (i, mybin(i), myoct(i), myhex(i), c)
39 else:
40     print "%5s\t%5s\t%5s\t%5s" % ("DEC", "BIN", "OCT", "HEX")
41     print ‘-‘ * 32
42     for i in range(begin, (end+1)):
43         print "%5d\t%5s\t%5s\t%5s" % (i, mybin(i), myoct(i), myhex(i))

8-13：稍后更新