class TreeNode {
      int val;
     TreeNode left;
      TreeNode right;
      TreeNode(int x) { val = x; }
  }

public class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        if(inorder==null||inorder.length==0) return null;

        return buildBinaryTree(inorder,0
 
,inorder.length-1,postorder,0,postorder.length-1);
    }
    //遞迴呼叫重構二叉樹
    private TreeNode buildBinaryTree(int[]inorder,int inleft,int inRight,int[]postorder,int postLeft,int postRight){

        if(inleft>inRight)
            return null;
        TreeNode root=new TreeNode(postorder[postRight]);
        //只有一個節點，直接返回root
 

        if(inleft==inRight)
            return root;
        int rootNum=0;
        for(int i=inleft;i<=inRight;i++){
           if(inorder[i]==postorder[postRight]){
               rootNum=i;
               break;
           }
        }
        int leftLength=rootNum-inleft;
        //遞迴呼叫左子樹和右子樹
        root.left=buildBinaryTree(inorder,inleft,inleft+leftLength-1
 
,postorder,postLeft,postLeft+leftLength-1);
        root.right=buildBinaryTree(inorder,inleft+leftLength+1,inRight,postorder,postLeft+leftLength,postRight-1);

        return root;
    }

    public static void main(String[]args){
        System.out.println("Hello World!");

    }
}