python回溯法实现数组全排列输出，python回溯,from sys imp

python回溯法实现数组全排列输出，python回溯,from sys imp

from sys import stdout#code from http://www.byrx.net/codes/def perm(li, start, end):    if(start == end):        for elem in li:            stdout.write(elem)        print ''    else:        for i in range(start, end):            li[start], li[i] = li[i], li[start]            perm(li, start+1, end)            li[i], li[start] = li[start], li[i]if __name__ == '__main__':    li = ['a','b','c','d']    perm(li, 0, len(li))