mirror of
https://github.com/TheAlgorithms/Python.git
synced 2025-07-05 09:21:13 +08:00
Corrected the directory of Fractional Knapsack algorithm (#7086)
* Moved fractional knapsack from 'dynamic_programming' to 'greedy_methods' * Updated DIRECTORY.md
This commit is contained in:
@ -1,27 +0,0 @@
|
||||
from bisect import bisect
|
||||
from itertools import accumulate
|
||||
|
||||
|
||||
def frac_knapsack(vl, wt, w, n):
|
||||
"""
|
||||
>>> frac_knapsack([60, 100, 120], [10, 20, 30], 50, 3)
|
||||
240.0
|
||||
"""
|
||||
|
||||
r = 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)
|
||||
return (
|
||||
0
|
||||
if k == 0
|
||||
else sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
|
||||
if k != n
|
||||
else sum(vl[:k])
|
||||
)
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
import doctest
|
||||
|
||||
doctest.testmod()
|
@ -1,53 +0,0 @@
|
||||
# https://en.wikipedia.org/wiki/Continuous_knapsack_problem
|
||||
# https://www.guru99.com/fractional-knapsack-problem-greedy.html
|
||||
# https://medium.com/walkinthecode/greedy-algorithm-fractional-knapsack-problem-9aba1daecc93
|
||||
|
||||
from __future__ import annotations
|
||||
|
||||
|
||||
def fractional_knapsack(
|
||||
value: list[int], weight: list[int], capacity: int
|
||||
) -> tuple[float, list[float]]:
|
||||
"""
|
||||
>>> value = [1, 3, 5, 7, 9]
|
||||
>>> weight = [0.9, 0.7, 0.5, 0.3, 0.1]
|
||||
>>> fractional_knapsack(value, weight, 5)
|
||||
(25, [1, 1, 1, 1, 1])
|
||||
>>> fractional_knapsack(value, weight, 15)
|
||||
(25, [1, 1, 1, 1, 1])
|
||||
>>> fractional_knapsack(value, weight, 25)
|
||||
(25, [1, 1, 1, 1, 1])
|
||||
>>> fractional_knapsack(value, weight, 26)
|
||||
(25, [1, 1, 1, 1, 1])
|
||||
>>> fractional_knapsack(value, weight, -1)
|
||||
(-90.0, [0, 0, 0, 0, -10.0])
|
||||
>>> fractional_knapsack([1, 3, 5, 7], weight, 30)
|
||||
(16, [1, 1, 1, 1])
|
||||
>>> fractional_knapsack(value, [0.9, 0.7, 0.5, 0.3, 0.1], 30)
|
||||
(25, [1, 1, 1, 1, 1])
|
||||
>>> fractional_knapsack([], [], 30)
|
||||
(0, [])
|
||||
"""
|
||||
index = list(range(len(value)))
|
||||
ratio = [v / w for v, w in zip(value, weight)]
|
||||
index.sort(key=lambda i: ratio[i], reverse=True)
|
||||
|
||||
max_value: float = 0
|
||||
fractions: list[float] = [0] * len(value)
|
||||
for i in index:
|
||||
if weight[i] <= capacity:
|
||||
fractions[i] = 1
|
||||
max_value += value[i]
|
||||
capacity -= weight[i]
|
||||
else:
|
||||
fractions[i] = capacity / weight[i]
|
||||
max_value += value[i] * capacity / weight[i]
|
||||
break
|
||||
|
||||
return max_value, fractions
|
||||
|
||||
|
||||
if __name__ == "__main__":
|
||||
import doctest
|
||||
|
||||
doctest.testmod()
|
Reference in New Issue
Block a user