文章目录

• 力扣算法学习day18-1
• • 669-修剪二叉搜索树
  • • 题目
    • 代码实现

力扣算法学习day18-1

669-修剪二叉搜索树

题目

代码实现

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public TreeNode trimBST(TreeNode root, int low, int high) {
        if(root == null){
            return null;
        }

        if(root.val < low){// 小于，找右子树中满足条件的
            return trimBST(root.right,low,high);
        }
        if(root.val > high){// 同理
            return trimBST(root.left,low,high);
        }

        // 上面都没有满足说明在low--high范围内
        root.left = trimBST(root.left,low,high);
        root.right = trimBST(root.right,low,high);

        return root;
    }
}