Binary Tree Inorder Traversal Problem & Solution

Given the `root` of a binary tree, return the inorder traversal of its nodes' values.

C++ Solution

``````#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")

static const int _=[](){std::ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();

/**
* 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> path;

inorderTraversal(root, path);

return path;
}

private:
void inorderTraversal(TreeNode* node, vector<int>& path) {
if (node == nullptr) {
return;
}

inorderTraversal(node->left, path);
path.push_back(node->val);
inorderTraversal(node->right, path);
}
};
``````