94. 二叉树的中序遍历

94. 二叉树的中序遍历

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题目链接：94. 二叉树的中序遍历

代码如下：

/**
 * 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> inorderTraversal(TreeNode* root) {
        vector<int> in;
        inorder(root,in);
        return in;
    }

    void inorder(TreeNode* root,vector<int>& in)
    {
        if(root==nullptr)
            return;
        
        inorder(root->left,in);
        in.push_back(root->val);
        inorder(root->right,in);
    }
};