Structure binary tree from inorder and postorder traversal for leetcode topic analysis

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

Note:

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

    int p;
    int[] postorder;
    int[] inorder;
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        this.p = postorder.length - 1;
        this.inorder = inorder;
        this.postorder = postorder;
        return buildTree(0, postorder.length);
    }
    TreeNode buildTree(int start, int end) {
        if (start >= end) {
            return null;
        }
        TreeNode root = new TreeNode(postorder[p]);
        int i;
        for (i = start; i < end && postorder[p] != inorder[i]; i++)
            ;
        p--;
        root.right = buildTree(i + 1, end);
        root.left = buildTree(start, i);
        return root;
    }