Question: 
Write a python function to find the sum of all odd length subarrays.


Model's Code:
def Odd_Length_Sum(arr):
    n = len(arr)
    total_sum = 0
    
    for length in range(1, n + 1, 2):
        for start in range(n - length + 1):
            total_sum += sum(arr[start:start + length])
    
    return total_sum



Sample Correct Code:
def Odd_Length_Sum(arr):
    Sum = 0
    l = len(arr)
    for i in range(l):
        Sum += ((((i + 1) *(l - i) + 1) // 2) * arr[i])
    return Sum


Asserts:
assert Odd_Length_Sum([1,2,4]) == 14
assert Odd_Length_Sum([1,2,1,2]) == 15
assert Odd_Length_Sum([1,7]) == 8


Tests:
Test 1 of 3: PASS
Test 2 of 3: PASS
Test 3 of 3: PASS

Test 782 of 974: 591/782 (75.57544757033247%): success