Given a List, perform summation of consecutive elements, by overlapping.
Input : test_list = [4, 7, 3, 2]
Output : [11, 10, 5, 6]
Explanation : 4 + 7 = 11, 7 + 3 = 10, 3 + 2 = 5, and 2 + 4 = 6.Input : test_list = [4, 7, 3]
Output : [11, 10, 7]
Explanation : 4+7=11, 7+3=10, 3+4=7.
Method 1 : Using list comprehension + zip()
In this, we zip list, with consecutive elements’ using zip() and then perform summation using + operator. The iteration part is done using list comprehension.
Python3
# initializing listtest_list = [4, 7, 3, 2, 9, 2, 1]# printing original listprint("The original list is : " + str(test_list))# using zip() to get pairing.# last element is joined with first for pairingres = [a + b for a, b in zip(test_list, test_list[1:] + [test_list[0]])]# printing resultprint("The Consecutive overlapping Summation : " + str(res)) |
The original list is : [4, 7, 3, 2, 9, 2, 1] The Consecutive overlapping Summation : [11, 10, 5, 11, 11, 3, 5]
Time Complexity: O(n) where n is the number of elements in the list “test_list”.
Auxiliary Space: O(1) additional space is not needed.
Method #2 : Using sum() + list comprehension + zip()
In this, we perform the task of getting summation using sum() and rest all functionalities kept similar to the above method.
Python3
# Python3 code to demonstrate working of # Consecutive overlapping Summation# Using sum() + list comprehension + zip()# initializing listtest_list = [4, 7, 3, 2, 9, 2, 1]# printing original listprint("The original list is : " + str(test_list))# using sum() to compute elements sum# last element is joined with first for pairingres = [sum(sub) for sub in zip(test_list, test_list[1:] + [test_list[0]])] # printing result print("The Consecutive overlapping Summation : " + str(res)) |
The original list is : [4, 7, 3, 2, 9, 2, 1] The Consecutive overlapping Summation : [11, 10, 5, 11, 11, 3, 5]
Method 3 : using a for loop
Python3
# Python3 code to demonstrate working of # Consecutive overlapping Summation# Using for loop# initializing listtest_list = [4, 7, 3, 2, 9, 2, 1]# printing original listprint("The original list is : " + str(test_list))# using for loop to compute consecutive overlapping summationn = len(test_list)res = [test_list[i] + test_list[(i+1) % n] for i in range(n)] # printing result print("The Consecutive overlapping Summation : " + str(res)) |
The original list is : [4, 7, 3, 2, 9, 2, 1] The Consecutive overlapping Summation : [11, 10, 5, 11, 11, 3, 5]
The time complexity of this approach is O(n), where n is the length of the list, since we iterate over the list once.
The auxiliary space complexity is also O(n), since we need to store the result list.
