SubsetsGenerator.java

package fun;

public class SubsetsGenerator {
    public static void main(String[] args) {
        String input = "cat";
        for (int i = 0; i <= input.length(); i++) {
            generateCombinations(input, "", 0, i);
        }
    }

    /**
     * Generates all combinations of the input string of a specific length using recursion.
     *
     * @param input   The input string for which combinations are to be generated.
     * @param current The current combination being built.
     * @param index   The current index in the input string.
     * @param length  The desired length of the combinations.
     */
    public static void generateCombinations(String input, String current, int index, int length) {
        if (current.length() == length) {
            System.out.println(current);
            return;
        }

        if (index == input.length()) {
            return;
        }

        // Exclude the current character
        generateCombinations(input, current, index + 1, length);

        // Include the current character
        generateCombinations(input, current + input.charAt(index), index + 1, length);
    }
}