MaxDepthTree.cpp

#include <iostream>
#include <memory>
#include <algorithm>

// 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:
    int maxDepth(TreeNode* root) {


        if (root==nullptr)
        {
            return 0;
        }

        int depthLeft = maxDepth(root->left);
        int depthRight = maxDepth(root->right);



    return std::max(depthLeft,depthRight) + 1;
    }

};
int main()
{

    std::unique_ptr<Solution> sol = std::make_unique<Solution>();

    TreeNode* root = new TreeNode(3);
    root->left = new TreeNode(9);
    root->right = new TreeNode(20);
    root->right->left = new TreeNode(15);
    root->right->right = new TreeNode(7);

    std::cout << sol->maxDepth(root) << std::endl;

    return 0;
}