三个习题

一、写一个程序，实现 abcd * 9 = dcba ，其中 a、b、c、d 都是数字

#!/usr/bin/env python
#-*- coding:utf-8 -*-

"实现：abcd * 9 = dcba"

for a in xrange(1，10):
    for b in xrange(10):
        for c in xrange(10):
            for d in xrange(10):
                abcd = a * 1000 + b * 100 + c * 10 + d
                dcba = d * 1000 + c * 100 + b * 10 + a
                if abcd * 9 == dcba:
                    print abcd
                else:
                    continue

二、写一个程序，实现九宫格，要求所有的行，列，对角线的和都为15

#!/usr/bin/env python
#-*- coding:utf-8 -*-

class NinePaper(object):
    def __init__(self):
        self.numbers = list()
        for i in range(1, 10):
            self.numbers.append(i)
        print("numbers = {0}".format(self.numbers))
    def run(self):
        lines = [(x,y,z) for x in self.numbers for y in self.numbers if x!=y for z in self.numbers if x!=z and y!=z and x+y+z == 15]
        for line1 in lines:
            for line2 in lines:
                if set(line1) & set(line2):
                    continue
                for line3 in lines:
                    if set(line1) & set(line2) & set(line3):
                        continue
                    if line1[0] + line2[0] + line3[0] != 15:
                        continue
                    if line1[1] + line2[1] + line3[1] != 15:
                        continue
                    if line1[2] + line2[2] + line3[2] != 15:
                        continue
                    if line1[0] + line2[1] + line3[2] != 15:
                        continue
                    if line1[2] + line2[1] + line3[0] != 15:
                        continue
                    print('''
            _____________
            |_{0}_|_{1}_|_{2}_|
            |_{3}_|_{4}_|_{5}_|
            |_{6}_|_{7}_|_{8}_|
            '''.format(line1[0], line1[1], line1[2], line2[0], line2[1], line2[2], line3[0], line3[1], line3[2],))

def main():
    ninePaper = NinePaper()
    ninePaper.run()

if __name__ == '__main__':
    main()

三、写一个程序，根据 UID 对 /etc/passwd 进行排序

#!/usr/bin/env python
#-*- coding:utf-8 -*-

import os
import codecs

class SortPasswd(object):
　　def __init__(self):
　　　　self.passwd = "passwd"
　　　　self.newpasswd = "newPasswd"
　　　　self.contextList = list()
　　　　if not os.path.exists(self.passwd):
　　　　　　print("please download passwd from linux.")
　　　　　　exit(1)
　　　　print("sort file is :{0}".format(self.passwd))
　　　　print("sorted file is :{0}".format(self.newpasswd))

　　def getContextList(self):
　　　　with codecs.open("passwd") as fr:
　　　　　　self.contextList += sorted(fr.readlines(), key=lambda line:int(line.split(":")[2]), reverse=False)
　　
　　def writeContextList(self):
　　　　with codecs.open("new_passwd", "w") as fw:
　　　　　　fw.writelines(self.contextList)

def main():
sortpasswd = SortPasswd()
sortpasswd.getContextList()
sortpasswd.writeContextList()

if __name__ == '__main__':
main()