## 2018年12月27日木曜日

### Algorithm - Python - 貪欲は良いことだ(重み付き科目、重ならない最大科目数、関数引数、貪欲アルゴリズム)

コード(Emacs)

Python 3

```#!/usr/bin/env python3
def get_courses_after(course: list, courses: list):
'''
>>> get_courses_after([9, 12, 3], courses)
[[12, 13, 1], [15, 16, 1], [16, 17, 1], [18, 20, 2], [17, 19, 2], [13, 20, 7]]
>>> get_courses_after([17, 19, 2], courses)
[]
'''
_, finish, _ = course
return [c for c in courses if c[0] >= finish]

def get_weight(courses: list) -> int:
'''
>>> get_weight(courses)
19
'''
return sum([weight for _, _, weight in courses])

def recursive_select(courses: list) -> list:
'''
>>> recursive_select(courses)
[[9, 12, 3], [12, 13, 1], [13, 20, 7]]
'''
if len(courses) == 0:
return []
weight = 0
for course in courses:
courses_after = get_courses_after(course, courses)
courses_tmp = [course] + recursive_select(courses_after)
weight_tmp = get_weight(courses_tmp)
if weight_tmp > weight:
weight = weight_tmp
selected_courses = courses_tmp
return selected_courses

if __name__ == '__main__':
import doctest

courses = [[8, 10, 1], [9, 12, 3], [11, 12, 1], [12, 13, 1], [15, 16, 1],
[16, 17, 1], [18, 20, 2], [17, 19, 2], [13, 20, 7]]
globs = globals()
globs.update({'courses': courses})
doctest.testmod(globs=globs)
```

```\$ ./sample2.py -v
Trying:
get_courses_after([9, 12, 3], courses)
Expecting:
[[12, 13, 1], [15, 16, 1], [16, 17, 1], [18, 20, 2], [17, 19, 2], [13, 20, 7]]
ok
Trying:
get_courses_after([17, 19, 2], courses)
Expecting:
[]
ok
Trying:
get_weight(courses)
Expecting:
19
ok
Trying:
recursive_select(courses)
Expecting:
[[9, 12, 3], [12, 13, 1], [13, 20, 7]]
ok
__main__
3 items passed all tests:
2 tests in __main__.get_courses_after
1 tests in __main__.get_weight
1 tests in __main__.recursive_select
4 tests in 4 items.
4 passed and 0 failed.
Test passed.
\$
```