Find Sum of All Contiguous Sublists in Python

Suppose we have a list of numbers called nums, now consider every contiguous subarray. Sum each of these subarray and return the sum of all these values. Finally, mod the result by 10 ** 9 + 7.

So, if the input is like nums = [3, 4, 6], then the output will be 43, as We have the following subarrays − [3] [4] [6] [3, 4] [4, 6] [3, 4, 6] The sum of all of these is 43.

To solve this, we will follow these steps −

• N:= size of nums
• ans:= 0
• for i in range 0 to size of nums, do
  • n:= nums[i]
  • ans := ans +(i+1) *(N-i) * n
• return (ans mod 1000000007)

Let us see the following implementation to get better understanding −

Example

 Live Demo

class Solution:
   def solve(self, nums):
      N=len(nums)
      ans=0
      for i in range(len(nums)):
         n=nums[i]
         ans += (i+1) * (N-i) * n
      return ans%1000000007
ob = Solution()
print(ob.solve([3, 4, 6]))

Input

[3, 4, 6]

Output

43