Python/dynamic_programming/fractional_knapsack.py

28 lines
584 B
Python
Raw Normal View History

2018-10-19 13:21:40 +00:00
from bisect import bisect
from itertools import accumulate
2018-10-19 13:21:40 +00:00
2019-10-05 05:14:13 +00:00
def frac_knapsack(vl, wt, w, n):
"""
>>> frac_knapsack([60, 100, 120], [10, 20, 30], 50, 3)
240.0
"""
2018-10-19 13:21:40 +00:00
2019-10-05 05:14:13 +00:00
r = list(sorted(zip(vl, wt), key=lambda x: x[0] / x[1], reverse=True))
vl, wt = [i[0] for i in r], [i[1] for i in r]
acc = list(accumulate(wt))
k = bisect(acc, w)
2019-10-05 05:14:13 +00:00
return (
0
if k == 0
else sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
2019-10-05 05:14:13 +00:00
if k != n
else sum(vl[:k])
)
if __name__ == "__main__":
import doctest
2018-10-19 13:21:40 +00:00
doctest.testmod()