Python 100例（001）

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

 '''有四个数字：1、2、3、4，能组成多少个互不相同且无重复数字的三位数？各是多少？'''
 n = 1
 num = [4, 2, 3, 1]
 list_num = [i * 100 + j * 10 + k for i in num for j in num for k in num if (i != j) and (j != k) and (i != k)]
 print('能组成%s个相互不同且无重复的数字的三位数' % len(list_num))
 print('它们分别是%s' % list_num)

 # 按照从小到大排序
 for i in xrange(len(list_num)):
     for j in xrange(len(list_num)):
         if list_num[i] < list_num[j]:
             list_num[i], list_num[j] = list_num[j], list_num[i]
 print('它们从小到大的顺序是%s' % list_num)

 # 求所有满足要求的三位数之和
 sum = 0
 for i in list_num:
     sum = sum + i
 print('它们的累计求和是%s' % sum)

 sum_0 = 0
 sum_1 = 0
 # 求所有偶数和
 for i in list_num:
     if i % 2 == 0:
         sum_0 = sum_0 + i
 print('所有偶数求和是%s' % sum_0)

 # 求所有奇数和
 for i in list_num:
     if i % 2 != 0:
         sum_1 = sum_1 + i
 print('所有偶数求和是%s' % sum_1)