1448. 统计二叉树中好节点的数目

╰半夏微凉° 2022-12-22 11:08 92阅读 0赞

# 题目来源 #

[1448. 统计二叉树中好节点的数目][1448.]

# 题目描述 #

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center]

# 题目解析 #

![在这里插入图片描述][20201119202347910.png_pic_center]

/**
     * 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 {
        
    private int count = 0;
        public int goodNodes(TreeNode root) {
        
            helper(root, Integer.MIN_VALUE);
            return count;
        }
        
        private void helper(TreeNode root, int val){
        
            if (root == null){
        
                return;
            }
            
            if (root.val >= val){
          // 注意这里是大于等于
                val = root.val;
                count++;
            }
            
            helper(root.left, val);
            helper(root.right, val);
        }
    }

[1448.]: https://leetcode-cn.com/problems/count-good-nodes-in-binary-tree/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poaXpoZW5nZ3Vhbg_size_16_color_FFFFFF_t_70_pic_center]: /images/20221120/bf115ba953e745bdb80f41a6e7185774.png
[20201119202347910.png_pic_center]: /images/20221120/e364de6f1de94c4894e7d039051628ca.png