update 0090.子集II：替换 go 代码，修改 python 的markdown语法错误

problems/0090.子集II.md

@@ -261,10 +261,10 @@ class Solution:
             self.path.pop()
 ```
 
-### Python3
+#### Python3
 
 不使用used数组
-```python3
+```python
 class Solution:
     def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
         res = []
@@ -291,7 +291,7 @@ class Solution:
 ```
 
 使用used数组
-```python3
+```python
 class Solution:
     def subsetsWithDup(self, nums: List[int]) -> List[List[int]]:
         result = []
@@ -315,26 +315,30 @@ class Solution:
 ### Go 
 
 ```Go
-var res[][]int
-func subsetsWithDup(nums []int)[][]int {
-	res=make([][]int,0)
-	 sort.Ints(nums)
-	dfs([]int{},nums,0)
-	return res
+var (
+    path   []int
+    res  [][]int
+)
+func subsetsWithDup(nums []int) [][]int {
+    path, res = make([]int, 0, len(nums)), make([][]int, 0)
+    sort.Ints(nums)
+    dfs(nums, 0)
+    return res
 }
-func dfs(temp, num []int, start int)  {
-	tmp:=make([]int,len(temp))
-	copy(tmp,temp)
 
-	res=append(res,tmp)
-	for i:=start;i<len(num);i++{
-		if i>start&&num[i]==num[i-1]{
-			continue
-		}
-		temp=append(temp,num[i])
-		dfs(temp,num,i+1)
-		temp=temp[:len(temp)-1]
-	}
+func dfs(nums []int, start int) {
+    tmp := make([]int, len(path))
+    copy(tmp, path)
+    res = append(res, tmp)
+
+    for i := start; i < len(nums); i++ {
+        if i != start && nums[i] == nums[i-1] {
+            continue
+        }
+        path = append(path, nums[i])
+        dfs(nums, i+1)
+        path = path[:len(path)-1]
+    }
 }
 ```