题目
分析
二叉树的先序遍历,用简单的递归即可过。
题解
/**
* 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> ans;
vector<int> preorderTraversal(TreeNode* root) {
if(root == NULL)
return ans;
ans.push_back(root->val);
preorderTraversal(root->left);
preorderTraversal(root->right);
return ans;
}
};