【LeetCode】Construct Binary Tree from Inorder and Postorder Traversal

Given inorder and postorder traversal of a tree, construct the binary tree.

Note:
You may assume that duplicates do not exist in the tree.

public class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        if(postorder.length==0||inorder.length==0)
            return null;
        return BuildTreeNode(inorder,0,inorder.length-1,postorder,0,postorder.length-1);
        
        
    }

    private TreeNode BuildTreeNode(int[] inorder, int instart, int inend,
            int[] postorder, int poststart, int postend) {
        if(inend<instart||postend<poststart)
            return null;
        int temp = postorder[postend];
        TreeNode root = new TreeNode(temp);
        int length = 0;
//注意搜索xiorder的开始和结束点
        for(int i=instart;i<=inend;i++){
            if(inorder[i]!=temp)
                length++;
            else if(inorder[i]==temp)
                break;
        }
        root.left=BuildTreeNode(inorder, instart, instart+length-1, postorder, poststart, poststart+length-1);
        root.right=BuildTreeNode(inorder, instart+length+1, inend, postorder, poststart+length, postend-1);
        return root;
    }
}