Could someone please tell me why the below code is leading to a WA?
This was my approach
Let sum[i] be the cumulative sum at index i of array arr. Note that I am indexing from 1, not 0. So sum[N] is the sum of all elements of the array.
There are 2 cases:
- sum[N] is a multiple of 3 and N>=3
Again 2 sub cases:
a) sum[N] = 0
Here, I calculate the number of 0s in the sum array excluding the last element (I don’t want an empty set at the end) which is stored in k. The answer is k*(k-1)/2 (all possible combinations of the 0s giving number of ways)
b) sum[N] not = 0
Both k and s are set 0. s gives the actual answer.
From the end of the sum array, if sum[i] is equal to 2/3rd of sum[N] increment k. Now, if we come across sum[i] which equals 1/3rd of sum[N] add k to s and continue till 1st element of sum array.
- sum[N] is not a multiple of 3 or N not >= 3
Answer is 0