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
/** * 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) return 0; return max(maxDepth(root->left),maxDepth(root->right))+1; } };非递归
class Solution { public: int maxDepth(TreeNode *root) { if(root == NULL) return 0; int res = 0; queue<TreeNode *> q; q.push(root); while(!q.empty()) { ++ res; for(int i = 0, n = q.size(); i < n; ++ i) { TreeNode *p = q.front(); q.pop(); if(p -> left != NULL) q.push(p -> left); if(p -> right != NULL) q.push(p -> right); } } return res; } };