1 /** 2  * Definition for binary tree 3  * struct TreeNode { 4  *     int val; 5  *     TreeNode *left; 6  *     TreeNode *right; 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} 8  * }; 9  */10 class Solution {11 public:12     void preOr(TreeNode * node, vector
     
       & rlt){13         if (node==NULL)14         return;15         rlt.push_back(node->val);16         preOr(node->left,rlt);17         preOr(node->right,rlt);18     }19     vector
      
        preorderTraversal(TreeNode *root) {20         // IMPORTANT: Please reset any member data you declared, as21         // the same Solution instance will be reused for each test case.22         vector
       
         rlt;23         preOr(root, rlt);24         return rlt;25     }26 };