Lintcode 16. Permutations II (Medium) (Python)

最新推荐文章于 2020-02-01 23:14:45 发布

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本文介绍了一种解决PermutationsII问题的方法，该问题要求在包含重复数字的列表中找到所有不重复的排列组合。通过使用递归深度优先搜索算法，并对输入进行排序来避免重复的排列。

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Permutations II

Description:

Given a list of numbers with duplicate number in it. Find all unique permutations.

Example
For numbers [1,2,2] the unique permutations are:

[
[1,2,2],
[2,1,2],
[2,2,1]
]
Challenge
Using recursion to do it is acceptable. If you can do it without recursion, that would be great!

Code:

class Solution:
    """
    @param: :  A list of integers
    @return: A list of unique permutations
    """

    def permuteUnique(self, nums):
        # write your code here
        res = []
        nums.sort()
        self.dfs(nums, [], res)
        return res

    def dfs(self, nums, path, res):
        if not nums:
            res.append(path)
        for i in range(len(nums)):
            if i>0 and nums[i-1]==nums[i]:
                continue
            self.dfs(nums[:i]+nums[i+1:], path+[nums[i]], res)