Data structures

data-structures.md

ArrayList

public class MyList<E> {

  private int size = 0;
  private static final int DEFAULT_CAPACITY = 10;
  private Object elements[];
  
  public MyList() {
    elements = new Object[DEFAULT_CAPACITY];
  }

  public void add(E e) {
    if (size == elements.length) {
      ensureCapa();
    }  
    elements[size++] = e;
  }
 

  private void ensureCapa() {
    int newSize = elements.length * 2;
    elements = Arrays.copyOf(elements, newSize);
  }

  @SuppressWarnings("unchecked")
  public E get(int i) {
    if (i>= size || i <0) {
      throw new IndexOutOfBoundsException("Index: " + i + ", Size " + i);
    }
    return (E) elements[i];
  }
}
 

Linked List

class Node {

  Node next = null;
  int data;
  
  public Node(int d) { 
    data = d; 
  }
  
  void appendToTail(int d) {
    Node end = new Node(d);
    Node n = this;
    while (n.next != null) { 
      n = n.next; 
    }
    n.next = end;
  }
}

Node deleteNode(Node head, int d) {
  
  Node n = head;
  
  if (n.data == d) {
    return head.next; /* moved head */
  }
  
  while (n.next != null) {
    if (n.next.data == d) {
      n.next = n.next.next;
      return head; /* head didn’t change */
    }
    n = n.next;
  }
}

Stack

public class Stack{
	
	Node top;
	
	public void add(int a){
		if (top == null){
			top = new Node(a);
		}else{
			top.next = top;
			top.value = a;
		}		
	}
	
	public void del(int a){
		
		Node2 current = top ;
		
		//if head
		if (top.value == a){
			top = top.next;
			return;
		}	
		
		while(current.next != null){
			if(current.next.value== a){
				current.next= current.next.next;
				return;
			}
			current = current.next;
		}
	}
	
	
	public void loop(){
		if (top == null){return;};
		
		Node2 current = top;
				
		while(current != null){
			System.out.println(current.value);
			current = current.next;
		}
	}
	
}

Queue

public class Queue{
	
	Node head;
		
	public void add(int a){
		
		Node2 nodeToAdd = new Node(a);
		
		if (head == null){
			head = nodeToAdd;
		}else{
			Node2 current = head ;
			while(current != null){
				if(current.next == null){
					current.next = nodeToAdd ;
					return;
				}else{
					current= current.next;
				}
			}
		}		
	}
	
	public void del(int a){
		
		Node2 current = head ;
		
		//if head
		if (head.value == a){
			head = head.next;
		}
		
		while(current.next != null){
			if(current.next.value== a){
				current.next= current.next.next;
				return;
			}
		}
	}
	
	public void loop(){
		if (head == null){return;};
		
		Node2 current = head;
				
		while(current != null){
			System.out.println(current.value);
			current = current.next;
		}
	}
	
}