生成四位不重复数字(0-9)的所有组合代码,Python代码库,德仔网

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【Python】生成四位不重复数字(0-9)的所有组合
作者:Duncan / 发布于2014/11/18/ 921

	#coding=cp936
	#关于这个问题的精彩讨论参见这里
	# <a href="http://groups.google.com/group/python-cn/browse_thread/thread/4d9eda8e422a6cf8">http://groups.google.com/group/python-cn/browse_thread/thread/4d9eda8e422a6cf8

	#在我的电脑上
	#init_set 1000 times 5.529
	#init_set2 1000 times 4.674
	#init_set3 1000 times 3.287
	#init_set4 1000 times 18.271
	#init_set5 1000 times 2.069

	def init_set8(r10=range(10)):
	 """
	 把循环内的range函数提到外面
	 times5.486 ==> 4.427
	 """
	 ret = []
	 for i in r10:
	 for j in r10:
	 for k in r10:
	 for l in r10:
	 if i != j and i != k and i != l and j != k and j != l and k != l:
	 ret.append((i, j, k, l))
	 return ret
	timing(init_set8, 1000)
	def init_set9(r10=range(10)):
	 """
	 for 循环改成列表推导
	 times5.486 ==>3.773
	 """
	 return [(i, j, k, l)
	 for i in r10
	 for j in r10
	 for k in r10
	 for l in r10
	 if ( i != j and i != k and i != l and j != k and j != l and k != l) ]
	timing(init_set9, 1000)

	def init_set10(r10=range(10)):
	 """
	 return 一个 generator
	 init_set10 1000 times 0.004
	 这个无疑是最快的 :P
	 我最喜欢这个解决方案,空间换时间的算法
	 对这个问题属于 过度优化
	 """
	 return ((i, j, k, l)
	 for i in r10
	 for j in r10
	 for k in r10
	 for l in r10
	 if( i != j and i != k and i != l and j != k and j != l and k != l) )
	timing(init_set10, 1000)

	def init_set11():
	 """
	 用代码的空间代价换取计算P4_4的时间
	 init_set11 1000 times 7.268 OMG
	 reduce(lambda x,y:x+y,l)太慢了
	 """
	 c10_4=[( i, j, k, l ) for i in xrange(0, 10)
	 for j in xrange(i+1, 10)
	 for k in xrange(j+1, 10)
	 for l in xrange(k+1, 10) ]

	 ret=reduce(lambda x,y:x+y,
	 [ [ (i, j, k, l),
	 (i, j, l, k),
	 (i, k, j, l),
	 (i, k, l, j),
	 (i, l, j, k),
	 (i, l, k, j),
	 (j, i, k, l),
	 (j, i, l, k),
	 (j, k, i, l),
	 (j, k, l, i),
	 (j, l, i, k),
	 (j, l, k, i),
	 (k, i, j, l),
	 (k, i, l, j),
	 (k, j, i, l),
	 (k, j, l, i),
	 (k, l, i, j),
	 (k, l, j, i),
	 (l, i, j, k),
	 (l, i, k, j),
	 (l, j, i, k),
	 (l, j, k, i),
	 (l, k, i, j),
	 (l, k, j, i),]
	 for i, j, k, l in c10_4 ],
	 )
	 return ret

	def init_set12():
	 """
	 generator是伟大的发明,数据流编程万岁
	 init_set12 1000 times 1.758
	 """
	 c10_4=(( i, j, k, l ) for i in xrange(0, 10)
	 for j in xrange(i+1, 10)
	 for k in xrange(j+1, 10)
	 for l in xrange(k+1, 10) )

	 from itertools import chain
	 ret=chain(
	 *( ( (i, j, k, l),
	 (i, j, l, k),
	 (i, k, j, l),
	 (i, k, l, j),
	 (i, l, j, k),
	 (i, l, k, j),
	 (j, i, k, l),
	 (j, i, l, k),
	 (j, k, i, l),
	 (j, k, l, i),
	 (j, l, i, k),
	 (j, l, k, i),
	 (k, i, j, l),
	 (k, i, l, j),
	 (k, j, i, l),
	 (k, j, l, i),
	 (k, l, i, j),
	 (k, l, j, i),
	 (l, i, j, k),
	 (l, i, k, j),
	 (l, j, i, k),
	 (l, j, k, i),
	 (l, k, i, j),
	 (l, k, j, i),)
	 for i, j, k, l in c10_4 )
	 )
	 return list(ret)
	timing(init_set12, 1000)
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　不重复数字　
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