题目：
题解：
func subsets(nums []int) (ans [][]int) {
set := []int{}
var dfs func(int)
dfs = func(cur int) {
if cur == len(nums) {
ans = append(ans, append([]int(nil), set...))
return
}
set = append(set, nums[cur])
dfs(cur + 1)
set = set[:len(set)-1]
dfs(cur + 1)
}
dfs(0)
return
}
