从中序遍历和后序遍历构建二叉树

class Solution {    public HashMap
     
       map = new HashMap<>();    public TreeNode buildTree(int[] inorder, int[] postorder) {        int len = postorder.length;        for(int i=0;i
      
       end) {            return null;        }        TreeNode root = new TreeNode(preorder[last]);        int middle = map.get(preorder[last]);        root.left = buildTree2(preorder,inorder,start,middle-1,last-1-(end-middle));        root.right = buildTree2(preorder,inorder,middle+1,end,last-1);        return root;    }}