题解 | #有重复项数字的全排列#

#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
#
# @param num int整型一维数组
# @return int整型二维数组
#
class Solution:
    def permuteUnique(self, nums: List[int]) -> List[List[int]]:
        # write code here
        ans = []
        path = []
        n = len(nums)
        on_path = [False] * n
        nums.sort()
        def dfs(i: int) -> None:
            if i == n:
                ans.append(path.copy())
                return
            for j in range(0, n):
                if on_path[j] or (j > 0 and nums[j] == nums[j - 1] and not on_path[j - 1]):
                    continue
                path.append(nums[j])
                on_path[j] = True
                dfs(i + 1)
                path.pop()
                on_path[j] = False
        dfs(0)
        return ans