LeetCode题解：Maximum Depth of Binary Tree

Maximum Depth of Binary Tree

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.

思路：

树其实是图的一种特例。

在对树进行搜索的时候保留树深的信息。一旦遇到深度比已知最大深度大时，就更新已知最大树深。

题解：

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    int max_depth;
    
    void traverse_depth(TreeNode* node, int depth)
    {
        if (node == nullptr)
        {
            if (depth > max_depth)
                max_depth = depth;
            return;
        }
        
        traverse_depth(node->left, depth + 1);
        traverse_depth(node->right, depth + 1);
    }
    
    int maxDepth(TreeNode *root) {
        max_depth = 0;
        
        traverse_depth(root, 0);
        return max_depth;
    }
};