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Spell Checker using TRIE






Spell checker program using TRIE data structure. Dictionary source is from Dictionary.txt, which is to be in the same directory of the program, or else change the file name and location



//Possible.java

import java.io.*;
import java.util.*;

class TrieNode {
    char letter;
    TrieNode[] links;
    boolean fullWord;

    TrieNode(char letter, boolean fullWord) {
        this.letter = letter;
        links = new TrieNode[26];
        this.fullWord = fullWord;
    }
}

public class Possible {

    static TrieNode createTree()
    {
        return(new TrieNode('', false));
    }

    static void insertWord(TrieNode root, String word)
    {
        int offset = 97;
        int l = word.length();
        char[] letters = word.toCharArray();
        TrieNode curNode = root;
        for (int i = 0; i < l; i++)
        {
            if (curNode.links[letters[i] - offset] == null)
                curNode.links[letters[i] - offset] = new TrieNode(letters[i], i == l - 1 ? true : false);
            curNode = curNode.links[letters[i] - offset];
        }
    }

    static boolean find(TrieNode root, String word)
    {
        char[] letters = word.toCharArray();
        int l = letters.length;
        int offset = 97;
        TrieNode curNode = root;
        int i;
        for (i = 0; i < l; i++)
        {
            if (curNode == null)
                return false;
            curNode = curNode.links[letters[i] - offset];
        }
        if (i == l && curNode == null)
            return false;
        if (curNode != null && !curNode.fullWord)
            return false;
        return true;
    }

    static void printTree(TrieNode root, int level, char[] branch, BufferedWriter out) throws IOException
    {
        if (root == null)
            return;
        for (int i = 0; i < root.links.length; i++)
        {
            branch[level] = root.letter;
            printTree(root.links[i], level + 1, branch, out);
        }
        if (root.fullWord)
        {
            for (int j = 1; j <= level; j++)
                out.write(branch[j]);
            out.write("n");
        }
    }

    public static void possible(TrieNode tree, String word) {
        Set<String> result = new HashSet<String>();
        // Remove a character
        for (int i = 0; i < word.length(); ++i)
            result.add(word.substring(0, i) + word.substring(i + 1));
        // Swap two consecutive characters
        for (int i = 0; i < word.length() - 1; ++i)
            result.add(word.substring(0, i) + word.substring(i + 1, i + 2) + word.substring(i, i + 1)
                    + word.substring(i + 2));
        // Replace a character with other
        for (int i = 0; i < word.length(); ++i)
            for (char c = 'a'; c <= 'z'; ++c)
                result.add(word.substring(0, i) + String.valueOf(c) + word.substring(i + 1));
        // Add a new character
        for (int i = 0; i <= word.length(); ++i)
            for (char c = 'a'; c <= 'z'; ++c)
                result.add(word.substring(0, i) + String.valueOf(c) + word.substring(i));
        ArrayList<String> res = new ArrayList<String>(result);
        int j = 0;
        for (int i = 0; i < result.size(); i++)
            if (find(tree, res.get(i))) {
                if (j == 0)
                    System.out.print("Do you mean : ");
                System.out.print(res.get(i) + " ");
                j++;
            }
    }

    public static void main(String[] args) throws IOException
    {
        TrieNode tree = createTree();
        long build1 = System.currentTimeMillis();
        File f = new File("Dictionary.txt");
        FileInputStream fread = new FileInputStream(f);
        BufferedReader br = new BufferedReader(new InputStreamReader(fread));
        String ele;
        while ((ele = br.readLine()) != null)
            insertWord(tree, ele);
        long build2 = System.currentTimeMillis();
        System.out.println("Time to build data structure is:" + (build2 - build1));
        BufferedReader br1 = new BufferedReader(new InputStreamReader(System.in));
        System.out.print("Enter the word :");
        String searchWord = br1.readLine();
        if (find(tree, searchWord))
        {
            System.out.println("The word was found");
        }
        else
        {
            long find1 = System.currentTimeMillis();
            possible(tree, searchWord);
            long find2 = System.currentTimeMillis();
            System.out.println("nTime to find possibilities is:" + (find2 - find1));
            System.out.println("Do you want to add this word to dictionary [y/n]: ");
            if (br1.readLine().equals("y")) {
                long add = System.currentTimeMillis();
                insertWord(tree, searchWord);
                long add1 = System.currentTimeMillis();
                try {
                    f.delete();
                    File f1 = new File("Dictionary.txt");
                    FileWriter fwrite = new FileWriter(f1, true);
                    BufferedWriter out = new BufferedWriter(fwrite);
                    char[] branch = new char[50];
                    printTree(tree, 0, branch, out);
                    out.close();
                } catch (Exception e) {
                    System.err.println("Error: " + e.getMessage());
                }
                long add2 = System.currentTimeMillis();
                System.out.println("Time to add a new word to Trie and file are:" + (add1 - add) + " " + (add2 - add1));
            }
        }
    }
}

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