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;}
};