Given a binary tree, find its maximum depth.

The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

递归求左右子树的高度取最大再加1即为所求

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int maxDepth(TreeNode* root) {
        if (root == NULL)
            return 0;
        int leftHeight = root->left ? maxDepth(root->left) : 0, rightHeight = root->right ? maxDepth(root->right) : 0;
        return max(leftHeight, rightHeight) + 1;
    }
};