LeetCode OJ刷题历程——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.
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以上是题目要求，下面贴出代码：

/**
* 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) {
int left,right;
if(root == NULL)
return 0;
left = maxDepth(root->left) + 1;
right = maxDepth(root->right) + 1;
return max(left,right);
}
};

此题考点为二叉树的深度优先遍历，利用递归最为容易理解。根的深度等于max(左子树和右子树的深度)+1，同时左子树的深度又可以用同样的公式来表示，因此可以用递归来求解。叶子节点的深度为1.