题解 | #岛屿数量#

/**
 * struct TreeNode {
 *    int val;
 *    struct TreeNode *left;
 *    struct TreeNode *right;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param root TreeNode类 
     * @return int整型
     */
    int maxDepth(TreeNode* root) {
        // write code here
        if(root == nullptr) // 递归返回临界
            return 0;
        return max(maxDepth(root->left), maxDepth(root->right)) + 1;
    }
};