leetcode-1448. 统计二叉树中好节点的数目

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
class Solution {
    int count = 0;
    public int goodNodes(TreeNode root) {
        dfs(root, Integer.MIN_VALUE);
        return count;
    }

    public void dfs(TreeNode root, int preMax){
        if (root == null) {
            return;
        }

        if (root.val >= preMax) {
            count++;
        }

        dfs(root.right, Math.max(preMax, root.val));
        dfs(root.left, Math.max(preMax, root.val));
    }
}