Sorting Strings and extracting common elements of two String arrays in Java

Question

I was asked to write down a Java function sharedStr that by given 2 sorted arrays of Strings, returns the number of Strings that appea

Answer 1

Go with the assumption that the two lists are sorted before entering your sharedStr algorithm. You'd want to keep two references: each to an element in each of the two lists.

Then you'd start comparing element after element and progress either or both of the references accordingly. Here's a pseudo-code:

def sharedStr(lista, listb):
    indexa = indexb = 0
    shared = 0

    while 1:
        try:
            a = lista[indexa]
            b = listb[indexb]
        except IndexError:     # we fell off one of the lists
            break

        if a == b:
            shared += 1
            indexa += 1
            indexb += 1
        elif a < b:
            indexa += 1
        else:    # b < a
            indexb += 1

    return shared

Yes, this is also a valid Python code. ;-)