144. 二叉树的前序遍历
题目图片
代码
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
void inorder(TreeNode* root, vector<int>& obj){
if(root == NULL){
return;
}
obj.push_back(root -> val);
inorder(root -> left, obj);
inorder(root -> right, obj);
}
vector<int> preorderTraversal(TreeNode* root) {
vector<int> obj;
inorder(root, obj);
return obj;
}
};