'''

class Solution

{

public:

int maxDepth(TreeNode* root)

{

```
int count=0;
if(root==nullptr)
return count;
else
{
queue<TreeNode*> q;
q.push(root);
while(!q.empty())
{
int s=q.size();
for(int i=0;i<s;i++)
{
TreeNode* t=q.front();
q.pop();
if(t->left) q.push(t->left);
if(t->right) q.push(t->right);
}
++count;
}
return count;
}
```

}

};