https://leetcode.com/problems/binary-tree-preorder-traversal/
Given a binary tree, return the preorder traversal of its nodes‘ values.
Example:
Input:[1,null,2,3]1 2 / 3 Output:[1,2,3]
Follow up: Recursive solution is trivial, could you do it iteratively?
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:
vector<int> preorderTraversal(TreeNode* root) {
vector<int> ans;
if(!root) return ans;
pre(ans, root);
return ans;
}
void pre(vector<int>& ans, TreeNode* root) {
ans.push_back(root -> val);
if(root -> left)
pre(ans, root -> left);
if(root -> right)
pre(ans, root -> right);
}
};
今天刷完了《妻子的浪漫旅行》 可以安心学习啦
#Leetcode# 144. Binary Tree Preorder Traversal
原文：https://www.cnblogs.com/zlrrrr/p/10121626.html