perfect sum count

class Solution{

    public:
    int perfectSum(int arr[], int n, int sum)
    {
        // Your code goes here
        sort(arr, arr+n);
        int i=0;
        while(i<n && arr[i]==0) i++;
        int*mew= new int[(sum+1)*(n+1)]();
        fill_n(mew, (sum+1)*(n+1), -1);
        return pow(2,i)*recurse(arr, n, sum, mew, n);
    }

    int recurse(int arr[], int n, int sum,int* mew, int N){
    if(mew[sum*N +n]!=-1)return mew[sum*N +n];
    if(sum==0)return 1;
    if(n<=0 || arr[n-1]==0) return 0;
    if(arr[n-1]<=sum) {
            int a = recurse(arr,n-1,sum-arr[n-1], mew, N);
            int b = recurse(arr,n-1,sum, mew, N);
            mew[sum*N +n]= a + b;
            return a+b;
        }
    mew[sum*N +n]= recurse(arr,n-1,sum, mew, N);
    return mew[sum*N +n];
    }
};