Question

Ok, so I’ve been trying to wrap my head around recursion in Java and I can accomplish easy tasks such as sum, reversing etc. but I have been struggling to do this exercise:

I’m trying to find the minimum number in an array using recursion but keep getting an answer of 0.0.

My understanding for recursion is that there I need to increment one element and then provide a base case that will end the recursion. I think I’m messing up when I have to return a value and when is best to call the recursion method.

This is what I have so far:

public static double findMin(double[] numbers, int startIndex, int endIndex) {

double min;
int currentIndex = startIndex++;

if (startIndex == endIndex)
    return numbers[startIndex];

else {
    min = numbers[startIndex];
    if (min > numbers[currentIndex]) {
        min = numbers[currentIndex];
        findMin(numbers, currentIndex, endIndex);
    }
            return min;
}       
} //findMin

Answer 1

There are a variety of problems in this code including:

• You don’t use the result of the recursive findMin call.
• startIndex will be the same for every call to findMin, because currentIndex is being set to the value of startIndex before startIndex is incremented.
• If the number at index 1 in the array is <= the number at index 0, you just return that number without even making the recursive call.