108. Convert Sorted Array to Binary Search Tree

Posted 2020-07-04 阿怪123

public class Solution {
    public TreeNode sortedArrayToBST(int[] nums) {
        
        int len=nums.length;

        TreeNode res=buildNode(0,len-1,nums);
        
        return res;
    }
    public TreeNode buildNode(int l,int r,int[] nums)
    {
        //使用递归的方式，终止条件是 左游标大于右游标
        if(l>r)
        {
            return null;
        }
        
        
        // 将左右值相等从终止结束条件中独立出来
        int mid=(l+r)/2;
        TreeNode temp=new TreeNode(nums[mid]);
        TreeNode left=buildNode(l,mid-1,nums);
        TreeNode right=buildNode(mid+1,r,nums);
        temp.left=left;
        temp.right=right;
        return temp;
    }
}