How to remove duplicate words in string without using array?

Question

Is there any way we can remove duplicate words from a String without using Arrays?

For example, I have this sentence "this is java programming program", and the output have to be "this java programming".

I see similar remove duplicate problems but all of them are using arrays.

I don't see any duplicate words in your sentence. Do you mean duplicate patterns? — Kyle Martin, Feb 19 '17 at 07:23
And even with patterns, why is the `i` in "programming" not removed (it appears earlier in the string)? — Henry, Feb 19 '17 at 07:24
I was thinking of the "mm", but yeah. Is there a minimum number of characters that need to match? — D M, Feb 19 '17 at 07:27
well, it is supposed to be words and substrings. In "this is", the "is" substring of "this". Same with "program" in "programming". I am supposed to check words separated by space. — Han, Feb 19 '17 at 07:35

score 2 · Answer 1 · answered Feb 19 '17 at 07:27

2

well, in Java, Strings are actually objects wrappers for character arrays which primarily add immutability.

so, there is no actual way to not use arrays for your task. even if you wrap your head around a solution which doesn't use any direct array creation in the code implementation, you will still be using arrays behind the scenes (if you want your solution to be optimal).

answered Feb 19 '17 at 07:27

omerkarj

663
2
7
18

That's technically correct but not especially helpful. – D M Feb 19 '17 at 07:28
1

@DM some solution explorations are just the wrong way to go. if you understand the reasoning for not doing it, why do it? – omerkarj Feb 19 '17 at 07:32
I agree with this train of thought. – Silverclaw Feb 19 '17 at 07:35
Thank you. I'm very new to java and this is a question issued by my teacher as a challenge. – Han Feb 19 '17 at 07:44
Surely the question is about direct, rather than indirect use of arrays. String could be a completely opaque class that doesn't use arrays. – pvg Feb 19 '17 at 07:53

score 1 · Answer 2 · edited Dec 25 '17 at 19:09

Remove duplicate words from a given string using simple way

package inffrd;

public class Q001 
{
    public static void removeduplicate(String input)
    {
        //convert the string to array by splitting it in words where space comes
        String[] words=input.split(" ");
        //put a for loop for outer comparison where words will start from "i" string
        for(int i=0;i<words.length;i++)
        {
            //check if already duplicate word is replaced with null
            if(words[i]!=null)
            {
                //put a for loop to compare outer words at i with inner word at j
                for(int j =i+1;j<words.length;j++)
                {
                    //if there is any duplicate word then make is Null
                    if(words[i].equals(words[j]))
                    {
                        words[j]=null;
                    }
                }
            }
        }
        //Print the output string where duplicate has been replaced with null
        for(int k=0;k<words.length;k++)
        {
            //check if word is a null then don't print it
            if(words[k]!=null)
            {
                System.out.print(words[k]+" ");
            }
        }
    }

    public static void main(String[] args) 
    {
        String s1="i am dinesh i am kumar";
        Q001.removeduplicate(s1);
    }
}

score 0 · Answer 3 · 2017-02-19T09:29:36.673

Below code will help you :)

public class RemDup
{
    public static void main ( String[] args )
    {
        String sentence = "this is java programming program";
        int max_word_length = sentence.length()/2;
        int min_word_length = 2;
        while(max_word_length>=min_word_length)
        {
        int si = 0;
        int ei = max_word_length;
        while ( ei<sentence.length() )
        {
            int e=ei;
            while ( e<sentence.length() )
            {
                int ind = sentence.indexOf ( sentence.substring ( si, ei ),e );
                if ( ind!=-1 )
                {
                    sentence = sentence.substring ( 0,ind ) +sentence.substring ( ind+max_word_length,sentence.length() );
                    e=ind+max_word_length;
                }
                else break;
            }


            si+=1;
            ei+=1;

        }
        max_word_length--;
        }
        System.out.println(sentence);
    }

}

Hi, It was ok for the "this is java programming program". But if we put longer sentences like "this is java programming program progress", it would output "this java programmingess" — Han, Feb 19 '17 at 09:58
Because, First 5 letters of Progress - "Progr" is the duplicate of first five letters of "Programming". Hence removed. — , Feb 19 '17 at 10:02
In case you want to handle those kind of stuation as well. Below is the updated code — , Feb 19 '17 at 10:32

score 0 · Accepted Answer · 2017-02-19T10:48:15.460

Below is the updated code @Han

public class RemDup
{
        public static void main ( String[] args )
        {
            String sentence = "this is java programming program progress";
            int max_word_length = sentence.length()/2;
            int min_word_length = 2;
            while(max_word_length>=min_word_length)
            {
            int si = 0;
            int ei = max_word_length;
            while ( ei<sentence.length() )
            {
                int e=ei;
                while ( e<sentence.length() )
                {
                    int ind = sentence.indexOf ( sentence.substring ( si, ei ),e );
                    if ( ind!=-1 )
                    {
                        if(
                         sentence.substring(ind-1,ind).equals(" ")
                        &((ind+max_word_length)>=sentence.length()||
                        sentence.substring(ind+max_word_length,ind+max_word_length+1).equals(" "))
                        )
                        {
                        sentence = sentence.substring ( 0,ind ) +sentence.substring ( ind+max_word_length,sentence.length() );
                        }
                        e=ind+max_word_length;

                    }
                    else break;
                }


                si+=1;
                ei+=1;

            }
            max_word_length--;
            }
            System.out.println(sentence);
        }

}

You should update your existing answer rather than add another — Dominic Cronin, Feb 19 '17 at 10:51

How to remove duplicate words in string without using array?

4 Answers4