how to check $1 and $2 subpatern exists or not in htacess

I want to implement htaccess rewriting for the following criteria

1. Url we are havi开发者_开发问答ng example.com/param1
2. Url we are having example.com/param1/param2

For url 1 I need to redirect to example.com/param1.php

For url 2 I need to redirect to example.com/param1/param2.php

How to write the htaccess code for this condition??

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RewriteRule ^(param1(/param2)?)$ /$1.php [R=301]