94. Binary Tree Inorder Traversal - medium
문제
Given a binary tree, return the inorder traversal of its nodes’ values. Example:
1
2
3
4
5
6
7
8
Input: [1,null,2,3]
1
\
2
/
3
Output: [1,3,2]
제한사항
입출력 예
풀이
- Tree, Recursive
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
/**
* 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:
// PreOrder : root -> left -> right
void preOrder(vector<int>& answer, TreeNode* node){
if(node == nullptr)
return;
answer.push_back(node->val);
preOrder(answer, node->left);
preOrder(answer, node->right);
}
// InOrder : left -> root -> right
void inOrder(vector<int>& answer, TreeNode* node){
if(node == nullptr)
return;
inOrder(answer, node->left);
answer.push_back(node->val);
inOrder(answer, node->right);
}
// PostOrder : left -> right -> root
void postOrder(vector<int>& answer, TreeNode* node){
if(node == nullptr)
return;
postOrder(answer, node->left);
postOrder(answer, node->right);
answer.push_back(node->val);
}
vector<int> inorderTraversal(TreeNode* root) {
vector<int> answer;
inOrder(answer, root);
return answer;
}
};