Given a collection of numbers, return all possible permutations.
For example,[1,2,3] have the following permutations:[1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], and [3,2,1].
用Python递归求全排列，回顾回顾
class Permutations: def perm(self, num, li, start, end): s = [] if start == end: for i in num: s.append(i) li.append(s) else: for i in range(start, end): num[start], num[i] = num[i], num[start] self.perm(num, li, start + 1, end) num[start], num[i] = num[i], num[start] # @param num, a list of integer # @return a list of lists of integers def permute(self, num): li = [] if len(num) == 0: return [] if len(num) == 1: return [num] self.perm(num, li, 0, len(num)) return li pe = Permutations() pe.permute([3, 2, 1])
原文：http://www.cnblogs.com/aboutblank/p/3989673.html