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130 lines
3.6 KiB
Python
130 lines
3.6 KiB
Python
"""
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Author : Alexander Pantyukhin
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Date : November 1, 2022
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Task:
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Given a list of days when you need to travel. Each day is integer from 1 to 365.
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You are able to use tickets for 1 day, 7 days and 30 days.
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Each ticket has a cost.
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Find the minimum cost you need to travel every day in the given list of days.
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Implementation notes:
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implementation Dynamic Programming up bottom approach.
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Runtime complexity: O(n)
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The implementation was tested on the
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leetcode: https://leetcode.com/problems/minimum-cost-for-tickets/
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Minimum Cost For Tickets
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Dynamic Programming: up -> down.
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"""
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import functools
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def mincost_tickets(days: list[int], costs: list[int]) -> int:
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"""
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>>> mincost_tickets([1, 4, 6, 7, 8, 20], [2, 7, 15])
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11
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>>> mincost_tickets([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [2, 7, 15])
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17
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>>> mincost_tickets([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [2, 90, 150])
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24
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>>> mincost_tickets([2], [2, 90, 150])
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2
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>>> mincost_tickets([], [2, 90, 150])
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0
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>>> mincost_tickets('hello', [2, 90, 150])
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Traceback (most recent call last):
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...
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ValueError: The parameter days should be a list of integers
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>>> mincost_tickets([], 'world')
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Traceback (most recent call last):
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...
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ValueError: The parameter costs should be a list of three integers
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>>> mincost_tickets([0.25, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [2, 90, 150])
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Traceback (most recent call last):
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...
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ValueError: The parameter days should be a list of integers
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>>> mincost_tickets([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [2, 0.9, 150])
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Traceback (most recent call last):
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...
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ValueError: The parameter costs should be a list of three integers
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>>> mincost_tickets([-1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [2, 90, 150])
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Traceback (most recent call last):
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...
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ValueError: All days elements should be greater than 0
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>>> mincost_tickets([2, 367], [2, 90, 150])
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Traceback (most recent call last):
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...
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ValueError: All days elements should be less than 366
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>>> mincost_tickets([2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [])
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Traceback (most recent call last):
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...
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ValueError: The parameter costs should be a list of three integers
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>>> mincost_tickets([], [])
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Traceback (most recent call last):
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...
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ValueError: The parameter costs should be a list of three integers
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>>> mincost_tickets([2, 3, 4, 5, 6, 7, 8, 9, 10, 30, 31], [1, 2, 3, 4])
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Traceback (most recent call last):
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...
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ValueError: The parameter costs should be a list of three integers
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"""
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# Validation
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if not isinstance(days, list) or not all(isinstance(day, int) for day in days):
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raise ValueError("The parameter days should be a list of integers")
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if len(costs) != 3 or not all(isinstance(cost, int) for cost in costs):
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raise ValueError("The parameter costs should be a list of three integers")
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if len(days) == 0:
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return 0
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if min(days) <= 0:
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raise ValueError("All days elements should be greater than 0")
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if max(days) >= 366:
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raise ValueError("All days elements should be less than 366")
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days_set = set(days)
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@functools.cache
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def dynamic_programming(index: int) -> int:
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if index > 365:
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return 0
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if index not in days_set:
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return dynamic_programming(index + 1)
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return min(
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costs[0] + dynamic_programming(index + 1),
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costs[1] + dynamic_programming(index + 7),
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costs[2] + dynamic_programming(index + 30),
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)
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return dynamic_programming(1)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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