【数据结构与算法】【LeetCode】【dfs+回溯】46.全排列

class Solution:
    def permute(self, nums):# nums: list[int] ,返回值：list[list[int]]
        # 定义路径列表，track
        if len(nums)==0:
            return []
        track=[]
        res=[]
        self.backtrack(nums,track,res)
        return res
    def backtrack(self,nums,track,res): # 回溯实现
        # 如果track长度等于nums长度，即一种选择，放入res中
        if len(track)==len(nums):
            res.append(track[:]) #  变量track列表指向是地址，深度优先遍历完成以后，回到了根结点，成为空列表。所以这里做一个拷贝
            return
        for i in range(len(nums)):
            if nums[i] in track:
                continue
                
            track.append(nums[i])
            self.backtrack(nums,track,res)
            track.pop()

if __name__=='__main__':
    nums=[1,2,3]
    a = Solution()
    print(a.permute(nums))