Subset Sum Doubt
Saptarick Mishra
58

Given an array of numbers check whether there exists a subset whose sum is equal to the target.
I wrote the following code and I am getting NullPointer Exception. I need help to figure out what is wrong with this.
"""
public class Main {

public static void main(String[] args) {
    int arr[] = {1,2,3};
    int n = arr.length;
    int target = 4;
    System.out.println(subsetSum(arr,target,0,0,new Boolean[n+1][target+1]));
}

public static Boolean subsetSum(int arr[] , int target , int index, int sum, Boolean dp[][]){
    if(index == arr.length){
        return false;
    }
    if(sum == target){
        return true;
    }
    if(dp[index][sum]){
        return dp[index][sum];
    }
    if(arr[index] + sum > target){
        dp[index][sum] = subsetSum(arr,target,index+1,sum,dp);
        return dp[index][sum];
    }
    dp[index][sum] = subsetSum(arr,target, index +1 , sum + arr[index],dp) ||
            subsetSum(arr,target,index+1,sum,dp);
    return dp[index][sum];
}

}

"""

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