diff --git a/src/main/java/com/thealgorithms/recursion/GenerateSubsets.java b/src/main/java/com/thealgorithms/recursion/GenerateSubsets.java index 5a3ff2e88040..0114a55e5b75 100644 --- a/src/main/java/com/thealgorithms/recursion/GenerateSubsets.java +++ b/src/main/java/com/thealgorithms/recursion/GenerateSubsets.java @@ -1,36 +1,52 @@ package com.thealgorithms.recursion; -// program to find power set of a string - import java.util.ArrayList; import java.util.List; +/** + * Utility class to generate all subsets (power set) of a given string using recursion. + * + *

For example, the string "ab" will produce: ["ab", "a", "b", ""] + */ public final class GenerateSubsets { private GenerateSubsets() { - throw new UnsupportedOperationException("Utility class"); } + /** + * Generates all subsets (power set) of the given string using recursion. + * + * @param str the input string to generate subsets for + * @return a list of all subsets of the input string + */ public static List subsetRecursion(String str) { - return doRecursion("", str); + return generateSubsets("", str); } - private static List doRecursion(String p, String up) { - if (up.isEmpty()) { - List list = new ArrayList<>(); - list.add(p); - return list; + /** + * Recursive helper method to generate subsets by including or excluding characters. + * + * @param current the current prefix being built + * @param remaining the remaining string to process + * @return list of subsets formed from current and remaining + */ + private static List generateSubsets(String current, String remaining) { + if (remaining.isEmpty()) { + List result = new ArrayList<>(); + result.add(current); + return result; } - // Taking the character - char ch = up.charAt(0); - // Adding the character in the recursion - List left = doRecursion(p + ch, up.substring(1)); - // Not adding the character in the recursion - List right = doRecursion(p, up.substring(1)); + char ch = remaining.charAt(0); + String next = remaining.substring(1); + + // Include the character + List withChar = generateSubsets(current + ch, next); - left.addAll(right); + // Exclude the character + List withoutChar = generateSubsets(current, next); - return left; + withChar.addAll(withoutChar); + return withChar; } }