shixiaoyu

public class TestClass {

 public TestClass() {

 print();

 public void print() {

 System.out.println(this.getClass() + ": a:" + this.a + ", b:" + this.b);

shixiaoyu

public class TestClass {

 public TestClass() {

 print();

 public void print() {

 System.out.println(this.getClass() + ": a:" + this.a + ", b:" + this.b);

shixiaoyu

public class TestClass {

 public TestClass() {

 print();

 public void print() {

 System.out.println(this.getClass() + ": a:" + this.a + ", b:" + this.b);

shixiaoyu

public class TestClass {

    int a;

    int b;

    public TestClass() {

        a = 5;

shixiaoyu

public class TestClass {

    int a;

    int b;

    public TestClass() {

        a = 5;

shixiaoyu

public class TestClass {

    int a;

    int b;

    public TestClass() {

        print();

shixiaoyu

private String y = "Possible";
private String n = "Impossible";
	
	
	public String ableToSolve(String s) {
		if (s == null) return n;
		if (s.isEmpty()) return y;
		if (s.length() % 2 != 0) return n;
		
		Stack<Character> stack = new Stack<Character>();

shixiaoyu

public class DeepIterator implements Iterator<Integer> {
	private Stack<Iterator> iteratorStack = new Stack<Iterator>();
	private Integer top = null;

	public DeepIterator(Iterable iterable){
		this.iteratorStack.push(iterable.iterator());
	}

	@Override
	public boolean hasNext() {

shixiaoyu

public static void main(String[] args){
		List list1 = new LinkedList();
		list1.add(0);
		list1.add(new LinkedList<Integer>());
		list1.add(1);
		list1.add(new LinkedList<Integer>());
		List list2 = new LinkedList();
		list2.add(list1);
		list2.add(2);

shixiaoyu

// This is the naive idea to serialize the tree into an array, modify the values, but keep the left/right child
// intact, but this uses extra O(N) space and O(N) time
public void serializeTreeSum(TreeNode node) {
    List<TreeNode> nodes = new ArrayList<>();
    this.inorderTraversal(node, nodes);

    // nodes is sorted ascendingly after inorder traversal, keep a rolling sum
    int rollingSum = 0;
    for (int i = nodes.size() - 1; i >= 0; i--) {
        nodes.get(i).val = nodes.get(i).val + rollingSum;