90. Subsets II ⭐

Medium

Given an integer array nums that may contain duplicates, return all possible

subsets (the power set).

The solution set must not contain duplicate subsets. Return the solution in any order.

Example 1:

Input: nums = [1,2,2]
Output: [[],[1],[1,2],[1,2,2],[2],[2,2]]

Example 2:

Input: nums = [0]
Output: [[],[0]]

Constraints:

• 1 <= nums.length <= 10

• -10 <= nums[i] <= 10

解題

func subsetsWithDup(nums []int) [][]int {
    sort.Ints(nums)

    ans := make([][]int, 0)

    var dfs func(int, []int)
    dfs = func(index int, cur []int) {
        ans = append(ans, append([]int{}, cur...))

        if index >= len(nums) { return }

        for i := index; i < len(nums); i++ {
            if i != index && nums[i] == nums[i - 1] { // 避免重複的subset
                continue
            }
            dfs(i + 1, append(cur, nums[i]))
        }
    }

    dfs(0, []int{})

    return ans
}