Bill Division HackerRank Solution in Java and Python with Explanation

Java and Python solution for Bill Division HackerRank problem

Problem Description :

Two friends Anna and Brian, are deciding how to split the bill at a dinner. Each will only pay for the items they consume. Brian gets the check and calculates Anna's portion. You must determine if his calculation is correct.

For example, assume the bill has the following prices bill = [2, 4, 6]. Anna declines to eat item k = bill[2] which costs 6.  If Brian calculates the bill correctly, Anna will pay (2 + 4) / 2 = 3.  If he includes the cost of bill[2], he will calculate (2 + 4 + 6) / 2 = 6.  In the second case, he should refund 3 to anna.

Complete the bonAppetit function in the editor below. It should print Bon Appetit if the bill is fairly split. Otherwise, it should print the integer amount of money that Brian owes Anna. 

bonAppetit has the following parameter(s):

• bill: an array of integers representing the cost of each item ordered
• k: an integer representing the zero-based index of the item Anna doesn't eat
• charged: the amount of money that Anna contributed to the bill

Example 1 :

Input :

size = 4
[3, 10, 2, 9]
k = 1 charged = 12

Output :

5

Example 2 :

Input :

size = 4
[3, 10, 2, 9]
k = 1 charged = 7

Output :

Bon Appetit

In this problem, we have to do sum of all numbers, minus Anna's declined item and split into 2. If split cost match with Anna paid to Brian then print "Bon Appetit" otherwise return overcharged price.

So lets jump on solution and its explanation.

Solution 1 : Bill Division Solution in Java

import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

    public static void bonAppetit(List<Integer> bill, int k, int charged) {
        
        int total = bill.stream().mapToInt(n -> n.intValue()).sum();
        int split = (total - bill.get(k)) / 2;
        
        if (split == charged) {
            System.out.println("Bon Appetit");
        } else {
            System.out.println(charged - split);
        }
    }

}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

        String[] firstMultipleInput = bufferedReader.readLine().replaceAll("\\s+$", "").split(" ");

        int n = Integer.parseInt(firstMultipleInput[0]);

        int k = Integer.parseInt(firstMultipleInput[1]);

        List<Integer> bill = Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
            .map(Integer::parseInt)
            .collect(toList());

        int b = Integer.parseInt(bufferedReader.readLine().trim());

        Result.bonAppetit(bill, k, b);

        bufferedReader.close();
    }
}

Code Explanation :

• We have used Stream api for get sum of all list values. Store into int total variable.
• Now minus the Anna's declined item from total sum and split into 2.
• Now, if given Anna's charged and split value matches then print "Bon Appetit" otherwise print integer amount of money that Brian owes Anna. 

Solution 2 :  Bill Division Solution in Python

def bonAppetit(bill, k, charged):
     
    s = (sum(bill)- bill[k])/2
    if s == charged:
        print("Bon Appetit")
    else:
        print(int((sum(bill)/2)-s))

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