leetcode/code/lc108.java at master · mJackie/leetcode · GitHub

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package code;

* 108. Convert Sorted Array to Binary Search Tree

* 题意：将有序数组转换为二叉搜索树

* 难度：Easy

* 分类：Tree, Depth-first Search

* 思路：类似二分查找，每次把数组劈成两半

* Tips：Bingo!

public class lc108 {

public class TreeNode {

int val;

TreeNode left;

TreeNode right;

TreeNode(int x) { val = x; }

}

public TreeNode sortedArrayToBST(int[] nums) {

TreeNode tn = helper(nums, 0, nums.length-1);

return tn;

}

public TreeNode helper(int[] nums, int left, int right){

if(left<right) return null;

int mid = (left+right)/2;

TreeNode tn = new TreeNode(nums[mid]);

tn.left = helper(nums, left, mid-1);

tn.right = helper(nums, mid+1, right);

return tn;

}

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