[LintCode] Maximum Depth of Binary Tree 二叉树的最大深度

 

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.

Example

Given a binary tree as follow:

  1
 / \ 
2   3
   / \
  4   5

The maximum depth is 3.

 

LeetCode上的原题,请参见我之前的博客Maximum Depth of Binary Tree

 

解法一:

class Solution {
public:
    /**
     * @param root: The root of binary tree.
     * @return: An integer
     */
    int maxDepth(TreeNode *root) {
        if (!root) return 0;
        return 1 + max(maxDepth(root->left), maxDepth(root->right));
    }
};

 

解法二:

class Solution {
public:
    /**
     * @param root: The root of binary tree.
     * @return: An integer
     */
    int maxDepth(TreeNode *root) {
        if (!root) return 0;
        int res = 0;
        queue<TreeNode*> q;
        q.push(root);
        while(!q.empty()) {
            ++res;
            int n = q.size();
            for (int i = 0; i < n; ++i) {
                TreeNode *t = q.front(); q.pop();
                if (t->left) q.push(t->left);
                if (t->right) q.push(t->right);
            }
        }
        return res;
    }
};

 

posted @ 2016-11-13 06:08 Grandyang 阅读(...) 评论(...) 编辑 收藏