An APL a day! - Put It In Reverse

Without much ado, today’s problem - Put it in Reverse

The find function X⍷Y identifies the beginnings of occurrences of array X in array Y.

In this problem, you’re asked to return a result that identifies the endings of occurrences of array X in array Y. To keep things simple, X and Y will be at most rank 1, meaning they’ll either be vectors or scalars.

Write a function that:

• takes a scalar or vector left argument
• takes a scalar or vector right argument
• returns a Boolean result that is the same shape as the right argument where 1’s mark the ends of occurrences of the left argument in the right argument

Examples:

      'abra' findEnd 'abracadabra'
0 0 0 1 0 0 0 0 0 0 1

      'issi' findEnd 'Mississippi'
0 0 0 0 1 0 0 1 0 0 0

      'bb' findEnd 'bbb bbb'
0 1 1 0 0 1 1

      (,42) findEnd 42
0

      42 findEnd 42
1

      (,42) findEnd ,42
1

      'are' 'aquatic' findEnd 'ducks' 'are' 'aquatic' 'avians' 
0 0 1 0

Solution

{⌽(⌽⍺)⍷⌽⍵}