درک بازگشت: تماس های عملکردی در داخل یک حلقه

public static void combinationSum(int[] candidates, int target, int start, List<Integer> temp, List<List<Integer>> result) {
    if (target == 0) {
        result.add(new ArrayList<>(temp));
        return;
    }
    for (int i = start; i < candidates.length; i++) { // Loop through elements
        if (target >= candidates[i]) {
            temp.add(candidates[i]);
            combinationSum(candidates, target - candidates[i], i, temp, result); // Recursive call inside loop
            temp.remove(temp.size() - 1);
        }
    }
}

public static void allSubsets(int[] nums, int index, List<Integer> temp, List<List<Integer>> result) {
    if (index == nums.length) {
        result.add(new ArrayList<>(temp));
        return;
    }
    temp.add(nums[index]);
    allSubsets(nums, index + 1, temp, result);
    temp.remove(temp.size() - 1);
    allSubsets(nums, index + 1, temp, result);
}

public static void subsetSum(int[] nums, int index, int sum, List<Integer> result) {
    if (index == nums.length) {
        result.add(sum);
        return;
    }
    subsetSum(nums, index + 1, sum + nums[index], result);
    subsetSum(nums, index + 1, sum, result);
}

public static void uniqueSubsets(int[] nums, int index, List<Integer> temp, Set<List<Integer>> result) {
    if (index == nums.length) {
        result.add(new ArrayList<>(temp));
        return;
    }
    temp.add(nums[index]);
    uniqueSubsets(nums, index + 1, temp, result);
    temp.remove(temp.size() - 1);
    uniqueSubsets(nums, index + 1, temp, result);
}

public static void uniqueSubsetSum(int[] nums, int index, int sum, Set<Integer> result) {
    if (index == nums.length) {
        result.add(sum);
        return;
    }
    uniqueSubsetSum(nums, index + 1, sum + nums[index], result);
    uniqueSubsetSum(nums, index + 1, sum, result);
}

public static void allPermutations(int[] nums, List<Integer> temp, boolean[] used, List<List<Integer>> result) {
    if (temp.size() == nums.length) {
        result.add(new ArrayList<>(temp));
        return;
    }
    for (int i = 0; i < nums.length; i++) { // Loop through elements
        if (!used[i]) {
            used[i] = true;
            temp.add(nums[i]);
            allPermutations(nums, temp, used, result); // Recursive call inside loop
            temp.remove(temp.size() - 1);
            used[i] = false;
        }
    }
}