1588. Sum of All Odd Length Subarrays - LeetCode Solution

class Solution:
    def sumOddLengthSubarrays(self, arr: List[int]) -> int:
        
        su = sum(arr)
        
        for j in range(3, len(arr)+1, 2):
            ptr1 = 0
            ptr2 = j
            while ptr2!= len(arr)+1:
                su+= sum(arr[ptr1 : ptr2])
                ptr1+=1
                ptr2+=1
        
        return su