LeetCode 108. 将有序数组转换为二叉搜索树 java题解

https://leetcode.cn/problems/convert-sorted-array-to-binary-search-tree/

class Solution {
    public TreeNode sortedArrayToBST(int[] nums) {
        int len=nums.length;
        return find(0,len-1,nums);//[0,len-1]构建树
        //返回根节点
    }
    public TreeNode find(int i,int j,int[] nums){
        if(i>j) return null;
        if(i==j) return new TreeNode(nums[i]);//只有一个结点了
        int mid=i+(j-i)/2;
        //找到中间的这个结点
        TreeNode node=new TreeNode(nums[mid]);
        if(i<=mid-1&&i>=0&&mid-1<nums.length)//边界判断其实冗余
            node.left=find(i,mid-1,nums);//构建左子树
        if(mid+1<=j&&mid+1>=0&&j<nums.length)
            node.right=find(mid+1,j,nums);//构建右子树
        return node;
    }
}