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。

/**
 * Definition for binary tree
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {        
        TreeNode root = reConstructBinaryTree(pre, 0, pre.length-1, in, 0, in.length-1);        
        return root;
    }
    
        private TreeNode reConstructBinaryTree(int[] pre, int startPre, int endPre, int[] in, int startIn, int endIn){
        if(startPre>endPre || startIn>endIn){
            return null;
        }
        
        TreeNode node = new TreeNode(pre[startPre]);
        for(int i=startIn; i<=endIn; i++){
            //找根节点
            if(in[i] == pre[startPre]){
                node.left = reConstructBinaryTree(pre, startPre+1, i-startIn+startPre, in, startIn, i-1);
                node.right = reConstructBinaryTree(pre, i-startIn+startPre+1, endPre, in, i+1, endIn);
                break; 
            }
        }
        return node;
    }
}