Swift Coding Challenge

codingchallenge.md

Given a grid layout of Basic Latin letters as follows:

   A B C D E
   F G H I J
   K L M N O
   P Q R S T
   U V W X Y
   Z

where A is at location (0,0), B is at location (0, 1), C is at (0, 2), N is at (2,3), and Z is at (5,0), write a function in Swift that outputs the "instructions" for typing out a given word. By "instructions" we mean that a cursor starts at location (0,0) and can only be moved like so:

• R - moves the cursor right
• L - moves the cursor left
• U - moves the cursor up
• D - moves the cursor down

There is 5th instruction:

• E - to accept the character under the cursor.

So one way to give instructions for the word "BAT" is:

   RELEDDDRRRRE

Starting at A, we go Right to get B then emit an E to accept the B. Then Left then Enter to get the A. Then three D's and four R's and finally an E to accept the T. You do not have to move back to the beginning.

You may not put the cursor over any row and column that does not have a letter. So if the cursor is on Z, you cannot move Right.

The Swift function should accept a string (like "BAT") and return the instruction string ("RELEDDDRRRRE"). Make sure to indicate if the input string is illegal in the proper idiomatic way.