// @Title: 从中序与后序遍历序列构造二叉树 (Construct Binary Tree from Inorder and Postorder Traversal)
// @Author: qisiii
// @Date: 2024-09-15 18:00:00
// @Runtime: 8 ms
// @Memory: 82.7 MB
// @comment: 
// @flag: 
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        if (postorder.length == 0) {
            return null;
        }
        TreeNode root = new TreeNode(postorder[postorder.length - 1]);
        if (postorder.length == 1) {
            return root;
        }
        int index = findIndex(inorder, root.val);
        root.left = buildTree(
                Arrays.copyOfRange(inorder, 0, index),
                Arrays.copyOfRange(postorder, 0, index));
        root.right = buildTree(
                Arrays.copyOfRange(inorder, index + 1, inorder.length),
                Arrays.copyOfRange(postorder, index, postorder.length-1));
        return root;
    }

    private int findIndex(int[] inorder, int target) {
        for (int i = 0; i < inorder.length; i++) {
            if (inorder[i] == target) {
                return i;
            }
        }
        return -1;
    }
}