leetcode--全排列

给定一个 没有重复 数字的序列，返回其所有可能的全排列

# -*- coding:utf-8 -*-

import copy

def permute(a_list, k):
    result, path = [], []

    def back():
        if len(path)==k:
            result.append(copy.deepcopy(path))
            print(path)
            return None

        for a in a_list:
            if a not in path:
                path.append(a)
                # print('### 1', path)
                back()
                path.pop()
    back()

    return result

permute(['a', 'b', 'c'], 2)