Binary Tree Inorder Traversal

问题：二叉树中序遍历

递归实现

/**

 * Definition for binary tree

 * struct TreeNode {

 *     int val;

 *     TreeNode *left;

 *     TreeNode *right;

 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}

 * };

 */

class Solution {

public:

    void InOrder(TreeNode *root,vector<int>&vec)

    {

        if(root==NULL) return ;

        InOrder(root->left,vec);

        vec.push_back(root->val);

        InOrder(root->right,vec);

    }

    vector<int> inorderTraversal(TreeNode *root) {

        vector<int>vec;

        InOrder(root,vec);

        return vec;

    }

};