Linkcode 97. 二叉树的最大深度

1
/ \
2   3
/ \
4    5

``
class Solution {
public:
/*
* @param root: A Tree
* @return: Preorder in ArrayList which contains node values.
*/
vector<int> min;
vector<int> preorderTraversal(TreeNode * root) {
// write your code here

if(root!=NULL){
min.push_back(root->val);

if((root->left)!=NULL) preorderTraversal(root->left);
if((root->right)!=NULL) preorderTraversal(root->right);

}
return min;

}
};