94. Binary Tree Inorder Traversal (Medium)

1.問題

• 給予一個binary tree, 回傳一個inorder traversal的node's序列

2.想法

• inorder traversal + recursive

3.程式碼

/**
 * 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> inorderTraversal(TreeNode* root) {
        vector<int> v;
        if (root) {
            inOrder(root, v);
        }
        return v;
    }
private:
    void inOrder(TreeNode* root, vector<int>& v) {
        if (root) {
            if (root->left) {
                inOrder(root->left, v);   
            }   
            v.push_back(root->val);
            if (root->right) {
                inOrder(root->right, v);   
            }    
        }
    }
};

4.Performance