假設輸入的前序遍歷和中序遍歷的結果中都不含重複的數字。例如輸入前序遍歷序列{1,2,4,7,3,5,6,8}和中序遍歷序列{4,7,2,1,5,3,8,6}，則重建二叉樹並返回。

package ssp;


class TreeNode {
	    int val;
	    TreeNode left;
	    TreeNode right;
	    TreeNode(int x) { val = x; }
}

class Solution {
    public TreeNode reConstructBinaryTree(int [] pre,int [] in) {
        
    	TreeNode root=create(pre,0,pre.length-1,in,0,in.length-1);
    	return root;
    	
    }

	private TreeNode create(int[] pre, int startPre, int endPre, int[] in, int startIn, int endIn) {
		// TODO Auto-generated method stub
		if(startPre>endPre||startIn>endIn)
		{
			return null;
		}
		TreeNode root=new TreeNode(pre[startPre]);
		for(int i=startIn;i<=endIn;i++)
		{
			if(pre[startPre]==in[i])
			{
				
				root.left=create(pre,startPre+1,startPre+i-startIn,in,startIn,i-1);
				root.right=create(pre,startPre+i-startIn+1,endPre,in,i+1,endIn);
				break;
			}
			
			
		}
		
		return root;
		
	}
	
	public void preOrder(TreeNode node){
		if(node != null){
			System.out.print(node.val+" ");
			preOrder(node.left);
			preOrder(node.right);
		}
	}

}
public class BinaryTree {

	public static void main(String [] args)
	{
		int [] pre={1,2,4,7,3,5,6,8};
		int [] in={4,7,2,1,5,3,8,6};
		Solution tool=new Solution();
	    TreeNode T=tool.reConstructBinaryTree(pre, in);
	    tool.preOrder(T);
	    
	}
	
    
	
}