Problem_6_Unique_Generalised_Abbreviation.java

package Subsets;

// Problem Statement: Unique Generalized Abbreviations (hard)
// LeetCode Question: 320. Generalized Abbreviation

import java.util.ArrayList;
import java.util.List;

public class Problem_6_Unique_Generalised_Abbreviation {
    class AbbreviatedWord {
        StringBuilder str;
        int start;
        int count;

        public AbbreviatedWord(StringBuilder str, int start, int count) {this.str = str;this.start = start;this.count = count;}}

        public List<String> generateGeneralizedAbbreviation(String word) {
            List<String> result = new ArrayList<String>();
            generateAbbreviationRecursive(word, new StringBuilder(), 0, 0, result);
            return result;
        }

        private static void generateAbbreviationRecursive(String word, StringBuilder abWord,
                                                          int start, int count, List<String> result) {
            if (start == word.length()) {
                if (count != 0)
                    abWord.append(count);
                result.add(abWord.toString());
            } else {
                // continue abbreviating by incrementing the current abbreviation count
                generateAbbreviationRecursive(word, new StringBuilder(abWord),
                        start + 1, count + 1, result);

                // restart abbreviating, append the count and the current character to the string
                if (count != 0)
                    abWord.append(count);
                generateAbbreviationRecursive(word,
                        new StringBuilder(abWord).append(word.charAt(start)), start + 1, 0, result);
            }
        }
}