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Python Program to find sum of array

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  • Difficulty Level : Easy
  • Last Updated : 27 Sep, 2022
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Given an array of integers, find the sum of its elements.

Examples:

Input : arr[] = {1, 2, 3}
Output : 6
1 + 2 + 3 = 6

Input : arr[] = {15, 12, 13, 10}
Output : 50

Method 1: Iterating through the array and adding each element to the sum variable and finally displaying the sum.

Python3




# Python 3 code to find sum
# of elements in given array
 
 
def _sum(arr):
 
    # initialize a variable
    # to store the sum
    # while iterating through
    # the array later
    sum = 0
 
    # iterate through the array
    # and add each element to the sum variable
    # one at a time
    for i in arr:
        sum = sum + i
 
    return(sum)
 
 
# driver function
arr = []
# input values to list
arr = [12, 3, 4, 15]
 
# calculating length of array
n = len(arr)
 
ans = _sum(arr)
 
# display sum
print('Sum of the array is ', ans)


Output:

Sum of the array is  34

Time complexity: O(n), Auxiliary Space: O(1)

Method 2: Using the built-in function sum(). Python provides an inbuilt function sum() which sums up the numbers in the list.

Syntax: 

sum(iterable) 

iterable: iterable can be anything list, tuples or dictionaries, but most importantly it should be numbered.

Python3




# Python 3 code to find sum
# of elements in given array
# driver function
arr = []
 
# input values to list
arr = [12, 3, 4, 15]
 
# sum() is an inbuilt function in python that adds
# all the elements in list,set and tuples and returns
# the value
ans = sum(arr)
 
# display sum
print('Sum of the array is ', ans)


Output:

Sum of the array is  34

Time complexity: O(n), Auxiliary Space: O(1)

Method 2: Using the reduce method. Array.reduce() method is used to iterate over the array and get the summarized result from all elements of array.

Syntax:

reduce( function, Array );

Python




from functools import reduce
# Python 3 code to find sum
# of elements in given array
 
 
def _sum(arr):
 
    # iterate over array
    # using reduce and get
    # sum on accumulator
    sum = reduce(lambda a, b: a+b, arr)
 
    return(sum)
 
 
# driver function
arr = []
# input values to list
arr = [12, 3, 4, 15]
 
# calculating length of array
n = len(arr)
 
ans = _sum(arr)
 
# display sum
print('Sum of the array is ', ans)


Output:

Sum of the array is  34

Please refer complete article on Program to find sum of elements in a given array for more details!


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