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Corrected the directory of Fractional Knapsack algorithm (TheAlgorith…
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…ms#7086)

* Moved fractional knapsack from 'dynamic_programming' to 'greedy_methods'

* Updated DIRECTORY.md
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SudhanshuSuman authored Oct 16, 2022
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4 changes: 2 additions & 2 deletions DIRECTORY.md
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* [Fast Fibonacci](dynamic_programming/fast_fibonacci.py)
* [Fibonacci](dynamic_programming/fibonacci.py)
* [Floyd Warshall](dynamic_programming/floyd_warshall.py)
* [Fractional Knapsack](dynamic_programming/fractional_knapsack.py)
* [Fractional Knapsack 2](dynamic_programming/fractional_knapsack_2.py)
* [Integer Partition](dynamic_programming/integer_partition.py)
* [Iterating Through Submasks](dynamic_programming/iterating_through_submasks.py)
* [Knapsack](dynamic_programming/knapsack.py)
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* [Test Min Spanning Tree Prim](graphs/tests/test_min_spanning_tree_prim.py)

## Greedy Methods
* [Fractional Knapsack](greedy_methods/fractional_knapsack.py)
* [Fractional Knapsack 2](greedy_methods/fractional_knapsack_2.py)
* [Optimal Merge Pattern](greedy_methods/optimal_merge_pattern.py)

## Hashes
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# 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()
# 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()

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