Algorithm optimization on arrays

Question

I am writing an algorithm that should return "yes" if a list of customers are to pay for a movie and receive their change (money) considering the the clerk starts receiving payments with an empty cashier pause, meaning he cant give change from the start. The movie costs 25 $ so if a customer has 50 $ the clerk has to refuse unless he has already received 25 $ from previous customer so is able to use that as change for the next customer.

I have such algorithm

public static String Tickets(int[] peopleInLine) {

    int sumOfMoneyWithCashier = 0;
    int cost = 25;

    for (int i = 0; i < peopleInLine.length; i++) {

        if (peopleInLine[i] == cost) {
            sumOfMoneyWithCashier += peopleInLine[i];
            if (peopleInLine[i + 1] == cost) {
                sumOfMoneyWithCashier += cost;
            } else if (peopleInLine[i + 1] > cost) {
                int change = peopleInLine[i + 1] - cost;
                if (sumOfMoneyWithCashier >= change) {
                    sumOfMoneyWithCashier -= change;
                } else {
                    System.out.println("no");
                    return "NO";
                }
            }
        } else if (peopleInLine[i] > cost) {
            int change = peopleInLine[i] - cost;
            if (sumOfMoneyWithCashier >= change) {
                sumOfMoneyWithCashier -= change;
            } else {
                System.out.println("no");
                return "NO";
            }
        }

    }
    System.out.println("YES");
    return "YES";
}

Now it works but not perfect , how can i improve this code so it check handles most of the scenario, ignore case where customer comes with less than 25. customers must come with multiples of 25 between range of {25, 50, 100} How can i make this code better is the question , i would appreciate an example code and explanation basically

Line.Tickets(new int[] {25, 25, 50}) // => YES 
Line.Tickets(new int[]{25, 100}) // => NO. Vasya will not have enough money to give change to 100 dollars
Line.Tickets(new int[] {25, 25, 50, 50, 100}) // => NO. Vasya will not have the right bills to give 75 dollars of change (you can't make two bills of 25 from one of 50)

How can I improve/make it better is a pretty vague question. If you have a specific situation when the program misbehaves or gives the wrong result than explain that situation (or situations) with example of given input and the result vs the expected result. — Joakim Danielson
– Joakim Danielson, Commented Dec 12, 2018 at 13:14
ok i got the task out of a codewars.com so there 12 tests it should pass , currently it passes 10 test , the problem is that codewars,com doesnt show you the tests inputs that were used @JoakimDanielson — valik
– valik, Commented Dec 12, 2018 at 13:18
(peopleInLine[i + 1] == cost) i am doing this to represent next element in the array @SamzSakerz — valik
– valik, Commented Dec 12, 2018 at 13:19
its just my way of getting next value in an array @SamzSakerz — valik
– valik, Commented Dec 12, 2018 at 13:28

SamHoque · Accepted Answer · 2018-12-12 13:28:47Z

3

This is a simple solution to what you are trying to do see if it works out for you :)

public static String Tickets(int[] peopleInLine) {
    int d25 = 0, d50 = 0;
    for (int aPeopleInLine : peopleInLine) {
        if (aPeopleInLine == 25){
            d25++;
        }
        if (aPeopleInLine == 50) {
            d25--;
            d50++;
        }
        if (aPeopleInLine == 100) {
            if (d50 > 0) {
                d50--;
                d25--;
            } else {
                d25 -= 3;
            }
        }
        if (d25 < 0){
            return "NO";
        }
    }
    return "YES";
}

answered Dec 12, 2018 at 13:28

SamHoque

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1 Comment

valik Over a year ago

yes it works perfectly for all cases , can you tell me the things wrong with code logic ? @SamzSakerz

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