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* Add doctests for fractional knapsack * Update greedy_methods/fractional_knapsack.py Co-authored-by: Christian Clauss <cclauss@me.com> * Run doctests * Update greedy_methods/fractional_knapsack.py Co-authored-by: Christian Clauss <cclauss@me.com> * Update greedy_methods/fractional_knapsack.py --------- Co-authored-by: Christian Clauss <cclauss@me.com>
52 lines
1.4 KiB
Python
52 lines
1.4 KiB
Python
from bisect import bisect
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from itertools import accumulate
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def frac_knapsack(vl, wt, w, n):
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"""
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>>> frac_knapsack([60, 100, 120], [10, 20, 30], 50, 3)
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240.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 10, 4)
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105.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 8, 4)
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95.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6], 8, 4)
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60.0
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>>> frac_knapsack([10, 40, 30], [5, 4, 6, 3], 8, 4)
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60.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 0, 4)
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0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 8, 0)
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95.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], -8, 4)
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0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 8, -4)
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95.0
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 800, 4)
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130
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>>> frac_knapsack([10, 40, 30, 50], [5, 4, 6, 3], 8, 400)
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95.0
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>>> frac_knapsack("ABCD", [5, 4, 6, 3], 8, 400)
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Traceback (most recent call last):
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...
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TypeError: unsupported operand type(s) for /: 'str' and 'int'
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"""
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r = sorted(zip(vl, wt), key=lambda x: x[0] / x[1], reverse=True)
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vl, wt = [i[0] for i in r], [i[1] for i in r]
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acc = list(accumulate(wt))
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k = bisect(acc, w)
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return (
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0
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if k == 0
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else sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
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if k != n
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else sum(vl[:k])
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)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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