10주차. solution - 김성주

public boolean isSymmetric(TreeNode root) {
        return recursive(root, root);
    }

    private boolean recursive(TreeNode left, TreeNode right) {

        if (Objects.isNull(left) && Objects.isNull(right)) {
            return true;
        }

        if (Objects.isNull(left) || Objects.isNull(right)) {
            return false;
        }

        if (left.val == right.val) {
            return recursive(left.right, right.left) && recursive(left.left, right.right);
        }
        return false;
    }

public void test() {
        int[] nums = {-1,0,1,2,-1,-4};
    }

    List<List<Integer>> result = new ArrayList<>();
    LinkedList<Integer> queue = new LinkedList<>();

    public List<List<Integer>> threeSum(int[] nums) {

        for (final int num : nums) {
            calculate(nums, num);
        }
        return null;
    }

    private void calculate(int[] nums, int value) {
        queue.add(value);
        if (queue.size() == 3) {
            final int sum = queue.stream()
                    .reduce(Integer::sum)
                    .get();
            if (sum == 0) {
                result.add(new ArrayList<>(queue));
            }
        }
    }