├── README.md
├── setup.py
└── skilift.py


/README.md:
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1 | # skilift
2 | 


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/setup.py:
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 1 | from setuptools import setup
 2 | 
 3 | setup(name='skilift',
 4 |       version='0.1.0',
 5 |       description='Simulate skilift',
 6 |       url='http://github.com/mattharrison/skilift',
 7 |       author='Matt Harrison',
 8 |       license='MIT',
 9 |       py_modules=['skilift'],
10 |       zip_safe=False)
11 | 


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/skilift.py:
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 1 | """
 2 | Code for simulating a lift at a ski resort:
 3 | 
 4 | >>> num_benches = 10
 5 | >>> bench_class = Quad
 6 | >>> lift = Lift(num_benches, bench_class)
 7 | >>> line = Line(num_people=10)
 8 | >>> lift.simulate(line)
 9 | {'loaded': 10, 'unloaded': 10, 'num_benches': 8}
10 | """
11 | 
12 | from collections import deque
13 | 
14 | 
15 | class Line:
16 | 
17 |     def __init__(self, num_people):
18 |         self.num_people = num_people
19 | 
20 |     def take(self, amount):
21 |         if amount > self.num_people:
22 |             amount = self.num_people
23 |         self.num_people -= amount
24 |         return amount
25 | 
26 |     def add(self, amount):
27 |         self.num_people += amount
28 | 
29 |     def __bool__(self):
30 |         return bool(self.num_people)
31 | 
32 | 
33 | class _Bench:
34 |     size = 1
35 | 
36 |     def __init__(self, id):
37 |         self.count = 0
38 |         self.id = id
39 | 
40 |     def load(self, num):
41 |         self.count += num
42 | 
43 |     def unload(self):
44 |         val = self.count
45 |         self.count = 0
46 |         return val
47 | 
48 | 
49 | class Quad(_Bench):
50 |     size = 4
51 | 
52 | 
53 | class Lift:
54 | 
55 |     def __init__(self, num_benches, bench_class):
56 |         half = num_benches / 2
57 |         self._up = deque()
58 |         self._down = deque()
59 |         for i in range(num_benches):
60 |             if i < half:
61 |                 self._up.append(bench_class(i))
62 |             else:
63 |                 self._down.append(bench_class(i))
64 |         self.bench_size = bench_class.size
65 | 
66 |     def people_riding_up(self):
67 |         return any(bench.count for bench in self._up)
68 | 
69 |     def simulate(self, line):
70 |         results = {"loaded": 0, "unloaded": 0, "num_benches": 0}
71 |         while line:
72 |             self.one_bench(line, results)
73 |         # get them to the top
74 |         while self.people_riding_up():
75 |             self.one_bench(line, results)
76 |         return results
77 | 
78 |     def one_bench(self, line, results=None):
79 |         results = results or {"loaded": 0, "unloaded": 0, "num_benches": 0}
80 |         num = line.take(self.bench_size)
81 |         # load bottom
82 |         bench = self._down.popleft()
83 |         bench.load(num)
84 |         self._up.append(bench)
85 |         results["loaded"] += num
86 |         # unload top
87 |         bench = self._up.popleft()
88 |         num = bench.unload()
89 |         results["unloaded"] += num
90 |         self._down.append(bench)
91 |         results["num_benches"] += 1
92 |         return results
93 | 
94 | 
95 | if __name__ == "__main__":
96 |     import doctest
97 | 
98 |     doctest.testmod()
99 | 


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