. Define an array to be cumulative if the nth (n > 0) element of the array is the sum of the first n elements of the array. So {1, 1, 2, 4, 8} is cumulative because

1. a[1] == 1 == a[0]
2. a[2] == 2 == a[0] + a[1]
3. a[3] == 4 == a[0] + a[1] + a[2]
4. a[4] == 8 == a[0] + a[1] + a[2] + a[4]

And {1, 1, 2, 5, 9} is not cumulative because a[3] == 5 != a[0] + a[1] + a[2]

Write a function named isCumulative that accepts an array of integers and returns 1 if the array is cumulative and 0 otherwise.

If you are programming in Java or C#, the function signature is int isCumulative(int[ ] a)

If you are programming in C or C++, the function signature is int isCumulative(int a[ ], int len) where len is the number of elements in the array

Some other examples:

if the input array is	isCumulative should return
{1}	0 (array must contain at least 2 elements)
{0,0,0,0,0,0}	1
{1, 1, 1, 1, 1, 1}	0
{3, 3, 6, 12, 24}	1
{-3, -3, -6, -12, -24}	1
{-3, -3, 6, 12, 24}	0