Python – Consecutive Missing elements Sum

Sometimes, we can get elements in range as input but some values are missing in otherwise consecutive range. We might have a use case in which we need to get summation of all the missing elements. Let’s discuss certain ways in which this can be done. Method #1 : Using list comprehension + sum() We can perform the task of finding missing elements using the range function to get the maximum element fill and then insert the elements if there is a miss. The summation is performed using sum(). 

Python3

# Python3 code to demonstrate
# Consecutive Missing elements Sum
# using list comprehension + sum()

# initializing list
test_list = [3, 5, 6, 8, 10]

# printing original list
print("The original list : " + str(test_list))

# using list comprehension + sum()
# Consecutive Missing elements Sum
res = sum([ele for ele in range(max(test_list) + 1) if ele not in test_list])

# print result
print("The sum of missing elements : " + str(res))

Output : 

The original list : [3, 5, 6, 8, 10]
The sum of missing elements : 23

Method #2 : Using set() + sum() This problem can also be performed using the properties of difference of set and then getting the elements that are missing in a range. The summation is performed using sum(). 

Python3

# Python3 code to demonstrate
# Consecutive Missing elements Sum
# Using set() + sum()

# initializing list
test_list = [3, 5, 6, 8, 10]

# printing original list
print("The original list : " + str(test_list))

# Using set() + sum()
# Consecutive Missing elements Sum
res = sum(list(set(range(max(test_list) + 1)) - set(test_list)))

# print result
print("The sum of missing elements : " + str(res))

Output : 

The original list : [3, 5, 6, 8, 10]
The sum of missing elements : 23