jingz8804

public class NaiveUnionFind{
    private int[] id;
    
    public NaiveUnionFind(int N){
      id = new int[N];
      for (int i = 0; i < N; i++){
          id[i] = i;
      }
    }
    

jingz8804

import java.util.Hashtable;

public class ThreeSum{
  private int[] numbers;
  private Hashtable<Integer, Boolean> numTable;
  
  public ThreeSum(int[] numbers){
    this.numbers = numbers;
    numTable = new Hashtable();
    for(int num: numbers){

jingz8804

import java.util.Iterator;
import java.util.NoSuchElementException;

public class LinkedListStack<Item> implements Iterable<Item> {
	private class Node {
		Item value;
		Node next;
	}

	private Node top;

jingz8804

import java.util.Iterator;
import java.util.NoSuchElementException;
public class ResizingArrayStack<Item> implements Iterable<Item>{
    private Item[] values;
    private int count;
    
    public ResizingArrayStack(){
        values = (Item[]) new Object[1]; // initialize the array to hold 1 element
        count = 0;
    }

jingz8804

import java.util.NoSuchElementException;
import java.util.Iterator;

public class LinkedListQueue<Item> implements Iterable<Item>{
    private class Node{
        Item item;
        Node next;
    }
    
    private Node head; // head of the queue; we dequeue at the head

jingz8804

import java.util.Iterator;
import java.util.NoSuchElementException;

public class ResizingArrayQueue<Item> implements Iterable<Item>{
    private Item[] items; // the actual array holding the items
    private int head; // the index of the head of the queue
    private int tail; // the index of the tail of the queue
    private int count; // the number of items in the queue
    
    public ResizingArrayQueue(){

jingz8804

import java.util.Arrays;
import java.util.ArrayList;

public class Subsets{
    public ArrayList<ArrayList<Integer>> subsets(int[] S) {
        // sort the array first
        Arrays.sort(S);
        ArrayList<ArrayList<Integer>> results = new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> emptySet = new ArrayList<Integer>();
        results.add(emptySet);

jingz8804

import java.util.Arrays;
public class Search2DMatrix{
    public boolean searchMatrixOne(int[][] matrix, int target){
        int numOfRows = matrix.length;
        int numOfColumns = matrix[0].length;
        
        if (numOfRows == 0 || numOfColumns == 0) return false;
        
        // here we assume that the total number of elements in the matrix 
        // is inside the range of Integer in Java

jingz8804

public class StockOne{
    // example: [5, 4, 1, 2, 8, 6, 9]
    public int maxProfit(int[] prices){
        if(prices.length <= 1) return 0;
        return maxProfitOne(prices);
        // return maxProfitTwo(prices, 0, prices[0], 0);
        // return maxProfitThree(prices, new Integer(-1), 0);
    }
    
    // this function use the iterative algorithm

jingz8804

import java.util.Iterator;
import java.util.NoSuchElementException;

public class Deque<Item> implements Iterable<Item>{
    private Item[] deck; // the array for the deck
    private int N; // the number of items in the deck
    private int head;
    private int tail;
    
    public Deque(){