重建二叉树

题目描述

输入某二叉树的前序遍历和中序遍历的结果，请重建出该二叉树。假设输入的前序遍历和中序遍历的结果中都不含重复的数字。例如输入前序遍历序列{1,2,4,7,3,5,6,8}和中序遍历序列{4,7,2,1,5,3,8,6}，则重建二叉树并返回。

代码

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
import java.util.*;
public class Solution {
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
        if(pre.length == 0 || in.length == 0){
            return null;
        }
        
        TreeNode t = new TreeNode(pre[0]);
        for(int i=0; i<in.length; i++){
            if(in[i] == pre[0]){
                t.left = reConstructBinaryTree( Arrays.copyOfRange(pre, 1, i+1), Arrays.copyOfRange(in, 0, i));
                t.right = reConstructBinaryTree( Arrays.copyOfRange(pre, i+1, pre.length), Arrays.copyOfRange(in, i+1, in.length));
            }
        }
        return t;
    }
}

标签：pre,遍历,TreeNode,int,copyOfRange,二叉树,重建
来源： https://blog.csdn.net/chechenshi/article/details/112594990