假定字符串S，以字符序列a1a2...an表示。例如： 对于字符串"abc", 全排列为cba bca bac cab acb abc
本文采用非递归方法分别给出Python版实现和C代码实现。
1 #!/usr/bin/python 2 import sys 3 4 def str2listuniq(s): 5 l = [] 6 for c in list(s): 7 if c not in l: 8 l.append(c) 9 return l 10 11 def insert_c2s(s, c): 12 l = [] 13 i = 0 14 while i <= len(s): 15 start = s[0:i] 16 end = s[i:] 17 e = start + c + end 18 l.append(e) 19 i += 1 20 return l 21 22 def list2allperms(l): 23 l_final = [l[0]] 24 for c in l[1:]: 25 l_cell = [] 26 for s in l_final: 27 l_cell.extend(insert_c2s(s, c)) 28 l_final = l_cell 29 return l_final 30 31 def main(argc, argv): 32 if argc != 2: 33 sys.stderr.write("Usage: %s <string>\n" % argv[0]) 34 sys.stderr.write(" e.g.: %s \"abc\"\n" % argv[0]) 35 return -1 36 37 if len(argv[1]) == 0: 38 sys.stderr.write("Oops, string is blank\n") 39 return -1 40 41 l_input = str2listuniq(argv[1]) 42 l_final = list2allperms(l_input) 43 if len(l_final) <= 24: 44 print ‘ ‘.join(l_final) 45 else: 46 print ‘ ‘.join(l_final[0:5]) + " ... " + l_final[-1] 47 print "\nThe total number of all permutation is %d" % len(l_final) 48 49 return 0 50 51 if __name__ == ‘__main__‘: 52 argc, argv = len(sys.argv), sys.argv 53 sys.exit(main(argc, argv))
测试结果：
$ ./foo.py a a The total number of all permutation is 1 $ ./foo.py ab ba ab The total number of all permutation is 2 $ ./foo.py abc cba bca bac cab acb abc The total number of all permutation is 6 $ ./foo.py abcd dcba cdba cbda cbad dbca bdca bcda bcad dbac bdac badc bacd dcab cdab cadb cabd dacb adcb acdb acbd dabc adbc abdc abcd The total number of all permutation is 24 $ ./foo.py abcde edcba decba dceba dcbea dcbae ... abcde The total number of all permutation is 120
用C代码实现比较复杂一些，因为要构造动态数组，wait for a while ...
原文：http://www.cnblogs.com/idorax/p/6391978.html