Kata

Dee is lazy but she's kind and she likes to eat out at all the nice restaurants and gastropubs in town. To make paying quick and easy she uses a simple mental algorithm she's called The Fair %20 Rule. She's gotten so good she can do this in a few seconds and it always impresses her dates but she's perplexingly still single. Like you probably.

This is how she does it:

• She rounds the price P at the tens place e.g:
  • 25 becomes 30
  • 24 becomes 20
  • 5 becomes 10
  • 4 becomes 0
• She figures out the base tip T by dropping the singles place digit e.g:
  • when P = 24 she rounds to 20 drops 0 T = 2
  • P = 115 rounds to 120 drops 0 T = 12
  • P = 25 rounds to 30 drops 0 T = 3
  • P = 5 rounds to 10 drops 0 T = 1
  • P = 4 rounds to 0 T = 0
• She then applies a 3 point satisfaction rating R to T i.e:
  • When she's satisfied: R = 1 and she'll add 1 to T
  • Unsatisfied: R = 0 and she'll subtract 1 from T
  • Appalled: R = -1 she'll divide T by 2, rounds down and subtracts 1

Your Task

Implement a method calc_tip that takes two integer arguments for price p

where 1 <= p <= 1000 and a rating r which is one of -1, 0, 1.

The return value T should be a non negative integer.

Note: each step should be done in the order listed.

Dee always politely smiles and says "Thank you" on her way out. Dee is nice. Be like Dee.