Maximum Depth of Binary Tree(leetcode)

题目：

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.

题目来源：https://oj.leetcode.com/problems/maximum-depth-of-binary-tree/

解题思路：1、广搜2、深搜，找出最大值

广搜代码：

#include<iostream>#include<queue>using namespace std;struct TreeNode {    int val;    TreeNode *left;    TreeNode *right;    TreeNode(int x) : val(x), left(NULL), right(NULL) {}};int maxDepth(TreeNode *root){int result=0;if(root==NULL)return result;queue<TreeNode *> q;q.push(root);int k=0,level=1;while(!q.empty()){k=level;level=0;for(int i=0;i<k;i++){if(q.front()->left!=NULL){q.push(q.front()->left);level++;}if(q.front()->right!=NULL){q.push(q.front()->right);level++;}q.pop();}result++;}return result;}int main(){TreeNode* root=new TreeNode(1);root->left=new TreeNode(2);root->right=new TreeNode(3);root->left->left=new TreeNode(4);root->right->left=new TreeNode(5);int results=maxDepth(root);system("pause");return 0;}

深搜代码：

#include<iostream>#include<stack>using namespace std;struct TreeNode {    int val;    TreeNode *left;    TreeNode *right;    TreeNode(int x) : val(x), left(NULL), right(NULL) {}};void dfs(TreeNode *root,int result,int &max){if(root==NULL){if(result>max)max=result;return ;}++result;dfs(root->left,result,max);dfs(root->right,result,max);}int maxDepth(TreeNode *root){int max=0;if(root==NULL)return max;int result=0;dfs(root,result,max);return max;}int main(){TreeNode* root=new TreeNode(1);root->left=new TreeNode(2);root->right=new TreeNode(3);root->left->left=new TreeNode(4);root->right->left=new TreeNode(5);int results=maxDepth(root);system("pause");return 0;}

利用栈进行迭代的算法以后再写。