题解 | #重建二叉树#数组copyOfRange

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param preOrder int整型一维数组
     * @param vinOrder int整型一维数组
     * @return TreeNode类
     */
    public TreeNode reConstructBinaryTree (int[] preOrder, int[] vinOrder) {
        // write code here
        if (preOrder.length == 0)    return null;

        TreeNode binaryTree = new TreeNode(preOrder[0]);
        int rootIndexInvin = 0;
        while (preOrder[0] != vinOrder[rootIndexInvin]) {
            rootIndexInvin++;
        }
        System.out.println(rootIndexInvin);
        // 左子树
        int[] dfsLeftVinOrder = new int[rootIndexInvin];
        int[] dfsLeftPreOrder = new int[rootIndexInvin];
        System.out.println(dfsLeftPreOrder.length);
        dfsLeftVinOrder = Arrays.copyOfRange(vinOrder, 0, rootIndexInvin);
        dfsLeftPreOrder = Arrays.copyOfRange(preOrder, 1, rootIndexInvin + 1);

        // 右子树
        int[] dfsRightVinOrder = new int[vinOrder.length - rootIndexInvin - 1];
        int[] dfsRightPreOrder = new int[preOrder.length - rootIndexInvin - 1];
        dfsRightVinOrder = Arrays.copyOfRange(vinOrder, rootIndexInvin + 1, vinOrder.length);
        dfsRightPreOrder = Arrays.copyOfRange(preOrder, 1 + rootIndexInvin, preOrder.length);
        binaryTree.left = reConstructBinaryTree(dfsLeftPreOrder, dfsLeftVinOrder);
        binaryTree.right = reConstructBinaryTree(dfsRightPreOrder, dfsRightVinOrder);

        return binaryTree;

    }

}