90. 子集 II

原题

https://leetcode.cn/problems/subsets-ii/description/

思路

回溯法 + 去重

复杂度

时间：O(C(n,n))
空间：O(C(n,n))

Python代码

class Solution:
    def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
        ans = []
        nums.sort()

        def dfs(start, path):
            ans.append(path[:])
            for i in range(start, len(nums)):
                if i > start and nums[i] == nums[i-1]:
                    continue 
                dfs(i+1, path + [nums[i]])
        
        dfs(0, [])
        return ans 
        

Go代码

func subsetsWithDup(nums []int) [][]int {
	var ans [][]int
	sort.Ints(nums)
	// 匿名函数
	var dfs func(int, []int)
	dfs = func(start int, path []int) {
		com := make([]int, len(path))
		copy(com, path)
		ans = append(ans, com)
		for i := start; i < len(nums); i++ {
			if i > start && nums[i] == nums[i-1] {
				continue
			}
			dfs(i+1, append(path, nums[i]))
		}
	}
	dfs(0, []int{})
	return ans
}