programming-examples/java/Data_Structures/Java Program to Implement Suffix Array.java

/*This Java program is to Implement Suffix arrayIn computer science, a suffix array is a sorted array of all suffixes of a string. It is a simple, yet powerful data structure which is used, among others, in full text indices, data compression algorithms and within the field of bioinformatics.*/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class SuffixArray
{
    private String[] text;
    private int length;
    private int[] index;
    private String[] suffix;

    public SuffixArray(String text)
    {
        this.text = new String[text.length()];
        for (int i = 0; i < text.length(); i++)
            {
                this.text[i] = text.substring(i, i+1);
            }
        this.length = text.length();
        this.index = new int[length];
        for (int i = 0; i < length; i++)
            {
                index[i] = i;
            }
        suffix = new String[length];
    }

    public void createSuffixArray()
    {
        for(int index = 0; index < length; index++)
            {
                String text = "";
                for (int text_index = index; text_index < length; text_index++)
                    {
                        text+=this.text[text_index];
                    }
                suffix[index] = text;
            }
        int back;
        for (int iteration = 1; iteration < length; iteration++)
            {
                String key = suffix[iteration];
                int keyindex = index[iteration];
                for (back = iteration - 1; back >= 0; back--)
                    {
                        if (suffix[back].compareTo(key) > 0)
                            {
                                suffix[back + 1] = suffix[back];
                                index[back + 1] = index[back];
                            }
                        else
                            {
                                break;
                            }
                    }
                suffix[ back + 1 ] = key;
                index[back + 1 ] = keyindex;
            }
        System.out.println("SUFFIX \t INDEX");
        for (int iterate = 0; iterate < length; iterate++)
            {
                System.out.println(suffix[iterate] + "\t" + index[iterate]);
            }
    }


    public static void main(String...arg)throws IOException
    {
        String text = "";
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("Enter the Text String ");
        text = reader.readLine();
        SuffixArray suffixarray = new SuffixArray(text);
        suffixarray.createSuffixArray();
    }
}

/*
Enter the Text String
banana

SUFFIX 	 INDEX
a         5
ana	  3
anana	  1
banana	  0
na	  4
nana	  2