输入二叉树的前序和中序数列，要求重构此二叉树？

1、遍历中序数列，根据前序数列找出左子树和右子树

2、左子树开始执行以上步骤、右子树开始执行以上步骤

代码如下：

public class BTreeSolution {
	
	public TreeNode reConstructBinaryTree(int[] pre,int[] in) {
		return reConBTree(pre,0,pre.length-1,in,0,in.length-1);
	}
	public TreeNode reConBTree(int[] pre,int preLeft,int preRight,int[] in,int inLeft,int inRight) {
		if(preLeft > preRight || inLeft > inRight) return null;
		TreeNode root = new TreeNode(pre[preLeft]);
		for(int i = inLeft ; i < inRight ; i++) {
			if(pre[preLeft] == in[i]) {
				root.left = reConBTree(pre,preLeft+1,preLeft+i-inLeft,in,inLeft,i-1);
				root.right = reConBTree(pre,preLeft+1+i-inLeft,preRight,in,i+1,inRight);
			}
		}
		return root;
	}
	
}
class TreeNode{
	int val;
	TreeNode left;
	TreeNode right;
	public TreeNode(int val) {this.val = val;}
}