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.

Difficulty: EASY
Starter code: def calc_tip(p, r):
	

Solutions:
def calc_tip(p, r):
	if p % 10 < 5:
		p //= 10
	else:
		p = p // 10 + 1
	if r == 1:
		tip = p + 1
	elif r == 0:
		tip = p - 1
	else:
		tip = int(p / 2) - 1
	return tip if tip >= 0 else 0


def calc_tip(p, r):
	if p % 10 < 5:
		p -= p % 10
	else:
		p += 10 - p % 10
	t = p / 10
	if r == 1:
		t += 1
	elif r == 0:
		t -= 1
	elif r == -1:
		t = int(t / 2) - 1
	return max(t, 0)


def calc_tip(p, r):
	t = round(p / 10 + 1e-08) * 10 / 10
	return max(0, t + 1 if r == 1 else t - 1 if r == 0 else t // 2 - 1)


def calc_tip(p, r):
	T = round(p / 10 + 0.01) * 10 // 10
	return max([T - 1, T + 1, T // 2 - 1][r], 0)


def calc_tip(p, r):
	if int(str(p)[-1]) < 5:
		p -= int(str(p)[-1])
	else:
		p += 10 - int(str(p)[-1])
	if len(str(p)) >= 2:
		T = int(str(p)[:-1])
	else:
		T = 0
	if r == 1:
		return T + 1
	elif r == 0:
		return max(T - 1, 0)
	else:
		return max(T // 2 - 1, 0)


def calc_tip(p, r):
	t = (p + 5) // 10
	return max(0, {1: t + 1, 0: t - 1, -1: t // 2 - 1}[r])


from math import floor

def calc_tip(p, r):
	t = floor(0.1 * p + 0.5)
	return max(0, {1: t + 1, 0: t - 1, -1: t // 2 - 1}[r])


def calc_tip(p, r):
	if 0 <= p % 10 <= 4:
		P = p // 10 * 10
	else:
		P = (p // 10 + 1) * 10
	T = P // 10
	if r == 1:
		return T + 1
	elif r == 0:
		return max(T - 1, 0)
	elif r == -1:
		return max(T // 2 - 1, 0)