CombinationSum.java

package LeetcodePractice;
import java.util.ArrayList;
import java.util.List;

public class CombinationSum {
    private static List<List<Integer>> combinationSum(int[] candidates, int target) {
        List<List<Integer>> result = new ArrayList<>();
        backtrack(candidates, target, 0, new ArrayList<>(), result);
        return result;
    }

    private static void backtrack(int[] candidates, int target, int start, List<Integer> current, List<List<Integer>> result) {
        if (target == 0) {
            result.add(new ArrayList<>(current)); 
            return;
        }

        for (int i = start; i < candidates.length; i++) {
            if (candidates[i] <= target) {
                current.add(candidates[i]);
                backtrack(candidates, target - candidates[i], i, current, result); 
                current.remove(current.size() - 1); 
            }
        }
    }

    public static void main(String[] args) {
        int[] candidates = {2, 3, 6, 7};
        int target = 12;

        List<List<Integer>> result = combinationSum(candidates, target);

        System.out.println("Combinations: " + result);
    }
    
}