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GOAL = 4
class Cup(object):
capacity = 1
contents = 0
def __init__(self, cap=1, cont=0):
"""
Makes cups ready for pouring.
:pre: Assumes that provided ``cap`` is positive.
0. Cup set up.
>>> c = Cup()
>>> c.capacity
1
>>> c.contents
0
1. Prevents cups being made with more water than capacity.
>>> d = Cup(cap=1, cont=2)
Traceback (most recent call last):
...
ValueError: Too much contents
2. Prevents cups going into negative water which would be bad.
>>> d = Cup(cap=1, cont=-2)
Traceback (most recent call last):
...
ValueError: Negative contents
"""
if cap < cont:
raise ValueError('Too much contents')
if cont < 0:
raise ValueError('Negative contents')
self.capacity = cap
self.contents = cont
@property
def space(self):
"""
>>> c = Cup(cap=3, cont=1)
>>> c.space
2
"""
return self.capacity - self.contents
def is_goal(self):
"""
Contains Goal amount
>>> c = Cup(cap=5, cont=4)
>>> c.is_goal()
True
"""
return self.contents == GOAL
def __eq__(self, c):
"""
NOTE does not care about types.
>>> c = Cup(cap=5, cont=4)
1. If either capacity or contents are different then not equal
>>> c == Cup(cap=6, cont=4)
False
>>> c == Cup(cap=5, cont=5)
False
2. If both are the same then equal
>>> c == Cup(cap=5, cont=4)
True
"""
return self.capacity == c.capacity and self.contents == c.contents
def pour_into(self, other_cup):
"""
Pour some / all content of this cup into other cup and make two new
cups.
1. If current cup is empty, nothing changes.
>>> c = Cup(cap=3, cont=0)
>>> d = Cup(cap=5, cont=1)
>>> e, f = c.pour_into(d)
>>> e == c
True
>>> f == d
True
2. If other cup is full, nothing changes.
>>> c = Cup(cap=3, cont=3)
>>> d = Cup(cap=5, cont=5)
>>> e, f = c.pour_into(d)
>>> e == c
True
>>> f == d
True
3. If other cup has space and this cup has water, then transition.
First cup is 5/5 and second cup is 0/3, this gives 2/5 and 3/3.
>>> c = Cup(cap=5, cont=5)
>>> d = Cup(cap=3, cont=0)
>>> e, f = c.pour_into(d)
>>> e.contents
2
>>> f.contents
3
"""
return (
Cup(
cap=self.capacity,
cont=self.contents-min(self.contents, other_cup.space)
),
Cup(
cap=other_cup.capacity,
cont=other_cup.contents+min(self.contents, other_cup.space)
)
)
def __repr__(self):
return "<Cup {}/{}>".format(self.contents, self.capacity)