94. Binary Tree Inorder Traversal

C++ |  Beat 100% | Inorder | Recursion 

/**

 * 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:

    vector<int>v;

    vector<int> inorderTraversal(TreeNode* root) {

        if(root==NULL)

            return v;

        inorderTraversal(root->left);

        v.push_back(root->val);

        inorderTraversal(root->right);

        return v;

    }

};