Prefix sum array in Python using accumulate function
We are given an array, find prefix sums of given array. Examples:
Input : arr = [1, 2, 3] Output : sum = [1, 3, 6] Input : arr = [4, 6, 12] Output : sum = [4, 10, 22]
A prefix sum is a sequence of partial sums of a given sequence. For example, the cumulative sums of the sequence {a, b, c, …} are a, a+b, a+b+c and so on. We can solve this problem in python quickly using accumulate(iterable) method.
Implementation:
Python3
# function to find cumulative sum of array from itertools import accumulate def cumulativeSum( input ): print ( "Sum :" , list (accumulate( input ))) # Driver program if __name__ = = "__main__" : input = [ 4 , 6 , 12 ] cumulativeSum( input ) |
Output
Sum : [4, 10, 22]
The time complexity of this cumulativeSum function is O(n), where n is the length of the input array.
The auxiliary space complexity of this function is also O(n), where n is the length of the input array.
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