Method that checks if the method was already executed with that input

Question

public class CatalanNumbers {

    private int howManyVariaties;
    private int catalanNumber;
    private int catalanNumber;

    public int catalan(int a) {
       if (Method was never executed with that input) {
              howManyVariaties++;
       int catalanNumber = 0;
       for (int i= 0; i < n; i++) {
           catalanNumber += catalan(i) * catalan( n- 1 -i);
       return catalanNumber

To sum it up I only want to check how the maximum stack depth is.

Can someone help me?

Joakim Danielson · Answer 1 · 2019-12-26T18:43:27.190

3

Add a Set to your class that keeps track of what input was used and check that set inside the method

public class CatalanNumbers {

    private int howManyVariaties;
    private int catalanNumber;
    private int catalanNumber;
    private Set<Integer> alreadyHandled = new HashSet<>();

    public int catalan(int a) {
        if (alreadyHandled.add(a)) {                  
            //rest of code
        }
    }
//...
}

edited Dec 26 '19 at 18:43

answered Dec 26 '19 at 18:22

Joakim Danielson

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1

Why adding linear complexity? Prefer ‘HashSet’ in given solution – Yurii J Dec 26 '19 at 18:34
I would suggest using Set instead of List. It will avoid duplicate elements. – Mehul Gayate Dec 26 '19 at 18:34
1

The problem is rather in contains() that takes O(n) instead of O(1), but anyway Set is more essential choice here :) – Yurii J Dec 26 '19 at 18:37
@YuriiJ You are correct, I will update my answer. Thanks. – Joakim Danielson Dec 26 '19 at 18:38
Sorry I have not expressed it properly. @YuriiJ said it perfectly. – Mehul Gayate Dec 26 '19 at 18:42

Method that checks if the method was already executed with that input

1 Answers1