Convert Sorted Array to Binary Search Tree
给一个sorted数组, 建立一个bst.
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/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ public class Solution { public TreeNode sortedArrayToBST(int[] nums) { return rec(nums, 0, nums.length - 1); } public TreeNode rec (int[] nums, int start, int end) { if(start > end) return null; int mid = start + (end - start) / 2; TreeNode root = new TreeNode(nums[mid]); root.left = rec(nums,start,mid-1); root.right = rec(nums,mid+1, end); return root; } } |