Make Possible sets of given strings in java

Question

I want to dynamically code for any no of strings.

For example if I am taking three strings "a" "b" "c"

I would like to get as result:

String []array= {"a", "b", "c", "a b", "b c", "a b c"};

(lack of "a c" is intended)

For four strings "a" "b" "c" "d" I would like to get as result

"a" "b" "c" "d" "a b" "b c" "c d" "a b c" "b c d" "a b c d"

Answer 1

So you want a set of all consecutive concatenations strings.

Say your input is an array of strings s = {s0, s1, s2, ..., sn} Now your result array of strings r will contain all elements of s.

r = s.copy()

now you add all consecutive concatenations with 2 strings

  for i = 0; i < n-1; i++;
    r.add(s[i] + s[i+1])

continue with all consecutive concatenations of 3 strings up to n strings

Answer 2

Since this looks like homework I will try to explain solution but you are the one who needs to create code.

---

If we have elements like

a, b, c, d

tokens using 1 elements will be

a b c d 
^ ^ ^ ^

tokens using 2 elements will be

a b c d
^^^
  ^^^
    ^^^

tokens using 3 elements will be

a b c d
^^^^^
  ^^^^^

and token using all 4 element will be

a b c d
^^^^^^^

So in case of each token of size n we are iterating from a, b, and adding to it its next n-1 elements.

So method which will generate all tokens of length n should work like this:

• for all elements from which we can create full tokens (if token size is 2 we can't use last element, if its size is 3 we can't use last 2 elements, ...)
  • get next n-1 elements and combine them in single token (collect that token in some collection so you can return it later)

Assuming that such method will be declared like List<String> generateTokens(String[] elements, int tokenSize)

for case

String[] elements = { "a", "b", "c", "d" };

we would need to invoke it 4 times to get

generateTokens(elements, 1) // ["a", "b", "c", "d"]
generateTokens(elements, 2) // ["a b", "b c", "c d"]
generateTokens(elements, 3) // ["a b c", "b c d"]
generateTokens(elements, 4) // ["a b c d"]

So as you see you need to invoke that method x times (where x is amount of elements) and gather in one place all results. You can easily achieve that with simple loop.

Answer 3

//Just you have to call possibleSetsOfString() to make possible sets.. and it will give u the possible sets in a one list...

public String concitinate(String st, int start, int end) {

    int i = start;
    int j = end + 1;
    entities = new ArrayList<String>(Arrays.asList(st.trim().split("\\s+")));

    String p = "";
    String num = "";
    for (int k = i; k < j; k++) {

        p += entities.get(k) + " ";

        num += +k + ",";


    }
    numbers.add(num);




    p = p.replaceAll("( )+", " ");
    return p.trim();
}

public ArrayList<String> possibleSetsOfString(String txt) {
    ArrayList<String> mylist = new ArrayList<String>();
    lengthOfString = countWords(txt);

    int k = 0;
    // int j=0;
    for (int i = 0; i < lengthOfString; i++) {
        for (int j = 0; j < lengthOfString - k; j++) {
            String s = concitinate(txt, j, j + k);
            mylist.add(s);


        }
        k++;
    }




    // Collections.sort(mylist, Collections.reverseOrder());

    Collections.reverse(mylist);
    Collections.reverse(numbers);

    return mylist;

}