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Python program to find Cumulative sum of a list

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  • Difficulty Level : Basic
  • Last Updated : 27 Aug, 2022
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The problem statement asks to produce a new list whose i^{th} element will be equal to the sum of the (i + 1) elements.

Examples : 
 

Input : list = [10, 20, 30, 40, 50]
Output : [10, 30, 60, 100, 150]

Input : list = [4, 10, 15, 18, 20]
Output : [4, 14, 29, 47, 67]

 

Approach 1 : 
We will use the concept of list comprehension and list slicing to get the cumulative sum of the list. The list comprehension has been used to access each element from the list and slicing has been done to access the elements from start to the i+1 element. We have used the sum() method to sum up the elements of the list from start to i+1.
Below is the implementation of the above approach : 
 

Python3




# Python code to get the Cumulative sum of a list
def Cumulative(lists):
    cu_list = []
    length = len(lists)
    cu_list = [sum(lists[0:x:1]) for x in range(0, length+1)]
    return cu_list[1:]
 
# Driver Code
lists = [10, 20, 30, 40, 50]
print (Cumulative(lists))


Output : 
 

[10, 30, 60, 100, 150]

Approach 2:
 

Python3




list=[10,20,30,40,50]
new_list=[]
j=0
for i in range(0,len(list)):
    j+=list[i]
    new_list.append(j)
     
print(new_list)
#code given by Divyanshu singh


Output : 
 

[10, 30, 60, 100, 150]

Time Complexity: O(n)

Auxiliary Space: O(n)
 


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