Finding maximum using recursion

Question

It gives me out of bound exception. And it seems not to recognize the first element in the array.

public class MaximumRec {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int[] A = {90, 45,12,19,72,55,15,19};
        int x = maximumR(A,8);
        System.out.print(x);

    }

    static int maximumR(int[] A, int n)
    {
        int max;
        if (n == 1)
        {
            return A[n];
        }
        else
        {
             max = maximumR(A, n-1);
             if(max < A[n] )
             {
                 max = A[n];
             }
        }
        return max;
    }

}

You need to start at 7, you only have 8 elements in your array. Arrays are 0 based, so you need to check if n==0. — kah608
– kah608, Commented Mar 29, 2018 at 21:25
Thank you. I just assigned 7 to n. However my output result is 72 instead of 90. I don't know what is wrong. — qad
– qad, Commented Mar 29, 2018 at 22:36

DarkAngel · Accepted Answer · 2018-03-29 21:27:22Z

1

It's because of the 8 you assign to n. And then you ask for the 8th element in the array, but the array starts counting at 0 so the A[8] doesn't exists. The max is A[7].

answered Mar 29, 2018 at 21:27

DarkAngel

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1 Comment

qad Over a year ago

Thank you, I just assigned 7 to n, however my output is 72, instead of 90. I can't figure out what is wrong

Jigar Patel · Accepted Answer · 2018-03-29 21:44:33Z

0

Java follows C-style indexing or Zero-based numbering in which index starts from 0 instead of 1. Also a good practice would be to dynamically assign the number instead of hard coding it.

e.g.

int x = maximumR(A, A.length - 1);

answered Mar 29, 2018 at 21:44

Jigar Patel

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2 Comments

qad Over a year ago

Thank you, I just assigned 7 to n, however my output is 72, instead of 90. I can't figure out what is wrong

Jigar Patel Over a year ago

It is because of your base condition in the recursion. The correct base condition in the recursion would be n==0 instead of n==1.

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