Posts in multiple Categories different single.php

I am smashing my head against some code.
Here is the situation:
I have one post in 3 different categories, this post has to be visible in “category 1” with the single1.php, in “category 2” with single2.php and in “category 3” with single3.php.

Obviously the 3 single.php pages have a different template inside.
For example the single1.php shows pictures and the_content(); single2.php shows pictures and comments; single3.php shows the reviews.

I know that in single.php I can use the if/else but I cannot figure out if the same post is in 3 different categories.

Any help please?

Instead of making it category specific you could use post formats and use different content-templates. In single.php you can write

<?php get_template_part( 'content', get_post_format() ); ?>

Then create different post formats

add_theme_support( 'post-formats', array( 'withpictures', 'withcomments' ) );

Then create different post templates content-withpictures.php, content-withcomments.php

When creating content the chosen post format will determine the template.