Create a popular post widget without plugin

In one of my wordpress project i need to create a wordpress popular post widget.Now i am giving the code to you.This code will show a list of most commented  post  without using a plugin.See the php code below. Just copy the above code and paste it to the function.php of your theme file.If your theme doesn't have function.php then create one. After  placing the code in your theme.Please click on the widget tab and you will see your popular post widget.You can give custom title and number of post to display. Happy hacking!