It is 2nd Question from Yesterday’s PayU Hiring Challenge on Hackerearth

**PROBLEM**

Given an array with size n and maximum value l compute

(\sum_{i=0}^{l} t_i * 31^l) **% mod**

where mod=10e9+7

t_i=size of maximum subset whose xor is i

If there is no subset whose xor is i then t_i=0

**Constraints**

n<=10^4

a[i]<=10^3

**Sample Example**

4

1 2 3 4

**Output**

3755653

**Explanation**

l=4

For i=0 31^0 * 3 Subset is (1,2,3)

For i=1 31^1 * 2 Subset is (2,3)

For i=2 31^2 * 2 Subset is (1,3)

For i=3 31^3 * 2 Subset is (1,2)

For i=4 31^4 * 4 Subset is (1,2,3,4)

I used DP to solve this problem but got WA

Here is link to my Solution

It would be grateful if someone can point out my mistake