Method comb

java/0040-combination-sum-ii.java:11–28

(
        int[] candidates,
        int target,
        List<List<Integer>> ans,
        List<Integer> ls,
        int index
    )

    }

    public void comb(
        int[] candidates,
        int target,
        List<List<Integer>> ans,
        List<Integer> ls,
        int index
    ) {
        if (target == 0) {
            ans.add(new ArrayList(ls));
        } else if (target < 0) return; else {
            for (int i = index; i < candidates.length; i++) {
                if (i > index && candidates[i] == candidates[i - 1]) continue;
                ls.add(candidates[i]);
                comb(candidates, target - candidates[i], ans, ls, i + 1);
                ls.remove(ls.get(ls.size() - 1));
            }
        }
    }
}