LintCode:把排序数组转换为高度最小的二叉搜索树

给一个排序数组（从小到大），将其转换为一棵高度最小的排序二叉树。

样例

给出数组 [1,2,3,4,5,6,7], 返回

     4   /   \  2     6 / \    / \1   3  5   7

挑战

可能有多个答案，返回任意一个即可

/** * Definition of TreeNode: * public class TreeNode { *     public int val; *     public TreeNode left, right; *     public TreeNode(int val) { *         this.val = val; *         this.left = this.right = null; *     } * } */ public class Solution{public TreeNode sortedArrayToBST(int[] num){if(num.length==0)return null;return sortedArrayToBST(num,0,num.length-1);}public TreeNode sortedArrayToBST(int[] num,int start,int end){if(start>end)return null;int mid=(start+end)/2;TreeNode root=new TreeNode(num[mid]);root.left=sortedArrayToBST(num,start,mid-1);root.right=sortedArrayToBST(num,mid+1,end);return root;}}