程式語言 - LeetCode - C - 1448. Count Good Nodes in Binary Tree

參考資訊：
https://www.cnblogs.com/cnoodle/p/14503186.html

題目：


解答：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     struct TreeNode *left;
 *     struct TreeNode *right;
 * };
 */

int dfs(struct TreeNode *n, int *r, int m)
{
    if (!n) {
        return -1;
    }

    if (n->val >= m) {
        (*r) += 1;
        m = n->val;
    }

    dfs(n->left, r, m);
    dfs(n->right, r, m);
    return 0;
}

int goodNodes(struct TreeNode* root)
{
    int r = 0;

    if (!root) {
        return 0;
    }

    dfs(root, &r, root->val);
    return r;
}