This one is showing run error for one testcase i have used cummulative sum approach effiecient one

Hi @Namanjain123

One test case is showing run error becz you have intialised the array in a wrong way before taking input of n from user. But still if you make it accurate then also there will be time limit exceed in one test case.

An efficient solution is :
Let there be a subarray (i, j) whose sum is divisible by n
sum(i, j) = sum(0, j) - sum(0, i-1)
Sum for any subarray can be written as q*n + rem where q is a quotient and rem is remainder
Thus,
sum(i, j) = (q1 * n + rem1) - (q2 * n + rem2)
sum(i, j) = (q1 - q2)n + rem1-rem2

We see, for sum(i, j) i.e. for sum of any subarray to be
divisible by n, the RHS should also be divisible by n.
(q1 - q2)n is obviously divisible by n, for (rem1-rem2) to
follow the same, rem1 = rem2 where
rem1 = Sum of subarray (0, j) % n
rem2 = Sum of subarray (0, i-1) % n

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