领扣（LeetCode）二叉树的中序遍历 个人题解

 1 class Solution {
 2     List<Integer> ans=new ArrayList<>();
 3     
 4     public List<Integer> inorderTraversal(TreeNode root) {
 5 
 6         midfs(root);
 7         return ans;
 8     }
 9     
10     private void midfs(TreeNode root) {
11         if(root==null)
12             return;
13         midfs(root.left);
14         ans.add(root.val);
15         midfs(root.right);
16     }
17 }