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43 lines
1.0 KiB
Python
43 lines
1.0 KiB
Python
# Kadane's algorithm
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def kadanes_algorithm(arr: list[int]) -> int:
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"""
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Function to find the maximum sum of a contiguous subarray using Kadane's algorithm
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>>> kadanes_algorithm([-2, 1, -3, 4, -1, 2, 1, -5, 4])
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6
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>>> kadanes_algorithm([-1, -2, -3, -4])
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-1
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>>> kadanes_algorithm([5, 4, -1, 7, 8])
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23
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>>> kadanes_algorithm([1])
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1
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>>> kadanes_algorithm([-1, 2, 3, -5, 4])
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5
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"""
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# initializing variables
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max_current = arr[0] # store the current max sum
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max_global = arr[0] # store the global max sum
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# looping through the array starting at the second element
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for i in range(1, len(arr)):
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# update current max sum by choosing the maximum between
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# current element alone or current element plus previous max
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max_current = max(arr[i], max_current + arr[i])
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# update global max sum if current max is larger
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max_global = max(max_current, max_global)
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return max_global
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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