LinkedList ADT

LinkedLists.java

class LinkedLists
{
  public static void main(String[] args) {
    LinkedList llist = new LinkedList();
    // Use LinkedLIst class API here
  }
}


class LinkedList
{
  Node ll;

  // Insert a node into a list
  public void insert(int val) {
    // Empty list case
    if(ll == null) {
      ll = new Node(val);
    } else {
      // Otherwise insert value at the head
      Node n = new Node(val);
      n.next = ll;
      ll = n;
    }
  }

  // Remove a node from a list given the value it contains
  public void remove(int val) {
    Node n = ll;

    // Empty list
    if(ll == null) {
      System.err.println("Couldn't find value to remove");
      return;
    }

    // First node is a match
    if(ll.val == val) {
      ll = ll.next;
      return;
    }

    // Iterate to find node with value
    while(n.next.val != val) {
      // Value not in list
      if(n.next == null) {
        System.err.println("Couldn't find value to remove");
        return;
      }
      n = n.next;
    }

    // Release the node from the list
    n.next = n.next.next;
  }

  // Reverse the list
  public void reverse() {
    Node p = ll;

    // Empty list or single node list
    if(p == null || p.next == null) {
      return;
    }

    // Thread the pointers backwards
    Node c = p.next;
    p.next = null;
    Node n = c.next;
    c.next = p;

    // Until we reach the end of the list
    while(n != null) {
      p = c;
      c = n;
      n = c.next;
      c.next = p;
    }

    ll = c;
  }

  public void printList() {
    Node n = ll;
    // Dump the node contents until we reach the end of the list
    while(n != null) {
      System.out.println("Node value: " + n.val);
      n = n.next;
    }
  }

  private int getSize() {
    Node n = ll;
    int size = 0;

    while(n != null) {
      size++;
      n = n.next;
    }

    return size;
  }
}


class Node
{
  int val;
  Node next;

  public Node(int val_) {
    val = val_;
  }
}