In this HackerRank Max Array Sum Interview preparation kit problem you have Given an array of integers, find the subset of non-adjacent elements with the maximum sum. Calculate the sum of that subset.

HackerRank Max Array Sum Interview preparation kit solution


Problem solution in Python programming.

#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the maxSubsetSum function below.
def maxSubsetSum(arr):
    dp = {} # key : max index of subarray, value = sum
    dp[0], dp[1] = arr[0], max(arr[0], arr[1])
    for i, num in enumerate(arr[2:], start=2):
        dp[i] = max(dp[i-1], dp[i-2]+num, dp[i-2], num)
    return dp[len(arr)-1]

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input())

    arr = list(map(int, input().rstrip().split()))

    res = maxSubsetSum(arr)

    fptr.write(str(res) + '\n')

    fptr.close()




Problem solution in Java Programming.

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.regex.*;

public class Solution {

    // Complete the maxSubsetSum function below.
    static int maxSubsetSum(int[] arr) {
     if(arr==null || arr.length==0)
      return 0;
     int n=arr.length;
     if(n==1)
       return arr[0];
      if(n==2)  //Just for clarification  not really need that
       return  Math.max(arr[0],arr[1]);  
    //will hold all max till the i-th location
      int[] g=new int[n];
      int currMax = Math.max(arr[0],arr[1]);
      g[0]=arr[0];
      g[1]=currMax;
      for (int i = 2; i < arr.length; i++) {
           currMax =  Math.max(g[i-2] + arr[i], currMax);
           currMax = Math.max(arr[i], currMax);
           g[i]=currMax; 

        }
    return g[n-1];
   // return IntStream.of(g).max().getAsInt();
}

    private static final Scanner scanner = new Scanner(System.in);

    public static void main(String[] args) throws IOException {
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int n = scanner.nextInt();
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        int[] arr = new int[n];

        String[] arrItems = scanner.nextLine().split(" ");
        scanner.skip("(\r\n|[\n\r\u2028\u2029\u0085])?");

        for (int i = 0; i < n; i++) {
            int arrItem = Integer.parseInt(arrItems[i]);
            arr[i] = arrItem;
        }

        int res = maxSubsetSum(arr);

        bufferedWriter.write(String.valueOf(res));
        bufferedWriter.newLine();

        bufferedWriter.close();

        scanner.close();
    }
}

Problem solution in C++ programming.

#include <bits/stdc++.h>

using namespace std;

vector<string> split_string(string);

// Complete the maxSubsetSum function below.
int dp[100005];

int maxSubsetSum(vector<int> arr) {
    
    dp[0]=max(0,arr[0]);
    if(arr.size()==1)
        return dp[0];
    for(int i=1;i<arr.size();i++)
    {
        dp[i]=max(dp[i-2],max(dp[i-1],dp[i-2]+arr[i]));
    }
    int n=arr.size();
    return max(dp[n-1],dp[n-2]);
}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    int n;
    cin >> n;
    cin.ignore(numeric_limits<streamsize>::max(), '\n');

    string arr_temp_temp;
    getline(cin, arr_temp_temp);

    vector<string> arr_temp = split_string(arr_temp_temp);

    vector<int> arr(n);

    for (int i = 0; i < n; i++) {
        int arr_item = stoi(arr_temp[i]);

        arr[i] = arr_item;
    }

    int res = maxSubsetSum(arr);

    fout << res << "\n";

    fout.close();

    return 0;
}

vector<string> split_string(string input_string) {
    string::iterator new_end = unique(input_string.begin(), input_string.end(), [] (const char &x, const char &y) {
        return x == y and x == ' ';
    });

    input_string.erase(new_end, input_string.end());

    while (input_string[input_string.length() - 1] == ' ') {
        input_string.pop_back();
    }

    vector<string> splits;
    char delimiter = ' ';

    size_t i = 0;
    size_t pos = input_string.find(delimiter);

    while (pos != string::npos) {
        splits.push_back(input_string.substr(i, pos - i));

        i = pos + 1;
        pos = input_string.find(delimiter, i);
    }

    splits.push_back(input_string.substr(i, min(pos, input_string.length()) - i + 1));

    return splits;
}