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

public class Solution {

    //将排序的二叉树转换成平衡二叉树
    public TreeNode sortedArrayToBST(int[] num) {
        if(num==null||num.length==0)  return  null; 

        return ArrayToBST(num,0,num.length-1);
    }
    //递归调用获得平衡二叉树
    public TreeNode ArrayToBST(int[]num,int start,int end){
        if(start>end) 
          return null;
        int mid=start+(end-start+1)/2; 
        TreeNode root=new TreeNode(num[mid]);
        root.left=ArrayToBST(num,start,mid-1);
        root.right=ArrayToBST(num,mid+1,end);
        return root;
    }

    public void inOrder(TreeNode root){

        if(root!=null){
            inOrder(root.left);
            System.out.println(root.val);
            inOrder(root.right);
        }
    }

    public static void main(String[]args){
      // System.out.println("Hello World!");
      int[]arr={1,2,3,4,5,6};
      Solution s=new Solution();
      s.inOrder(s.sortedArrayToBST(arr));
    }
}