94. 二叉树的中序遍历 (easy)

递归： 左根右

/**
* 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* node, vector<int>& v) {
if (node == NULL) return ;

if (node->left != NULL) Inorder(node->left, v);
v.push_back(node->val);
if (node->right != NULL) Inorder(node->right, v);

}

vector<int> inorderTraversal(TreeNode* root) {
vector<int> v;
 
Inorder(root, v);
return v;
}
};