力扣94-二叉树的中序遍历

二叉树的中序遍历

题目链接

解题思路

1. 递归解决
2. 先遍历左子树
3. 访问根节点
4. 再遍历右子树

/**
 * 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> ans;
    void def(TreeNode*root){
        if(root == nullptr) return;
        if(root->left != nullptr) def(root->left);
        ans.push_back(root->val);
        if(root->right != nullptr) def(root->right);
    }
    vector<int> inorderTraversal(TreeNode* root) {
        def(root);
        return ans;
    }
};