question24.java

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

public class question24 {
    public static void main(String[] args) {
        String input = "ABC";
        System.out.println(generatePermutations(input));
    }

    private static List<String> generatePermutations(String str) {
        List<String> permutations = new ArrayList<>();
        permutations.add(str);
        
        for (int i = 0; i < str.length(); i++) {
            List<String> newPermutations = new ArrayList<>();
            for (String perm : permutations) {
                for (int j = 0; j < perm.length(); j++) {
                    String swapped = swap(perm, i, j);
                    if (!newPermutations.contains(swapped)) {
                        newPermutations.add(swapped);
                    }
                }
            }
            permutations.addAll(newPermutations);
        }
        
        Collections.sort(permutations);
        return permutations;
    }

    private static String swap(String str, int i, int j) {
        char[] charArray = str.toCharArray();
        char temp = charArray[i];
        charArray[i] = charArray[j];
        charArray[j] = temp;
        return new String(charArray);
    }
}