New implementation of LinkedList

Author: cszach

README.md

@@ -4,27 +4,51 @@ Java data structures
 > Honorable mention to professor Eustrat Zhupa in the University of
 > Rochester Computer Science Department.
 
-Lists
+To-do
 -----
 
+### Lists
+
 - [x] Dynamic array
 - [x] Singly linked list
 - [ ] Doubly linked list
-- [ ] Queue
 - [ ] Stack
+- [ ] Queue
+- [ ] Hash table
 
-Trees
------
+### Trees
 
-- [ ] Tree
-- [ ] Binary tree
 - [ ] Binary search tree (BST)
-- [ ] Heap
+- [ ] Binary heap
+- [ ] Priority queue
 
-Sorting
--------
+### Graphs
 
-- [ ] Insertion sort
-- [ ] Selection sort
-- [ ] Merge sort
-- [ ] Quick sort
+- [ ] Graph
+- [ ] Trie
+
+### Algorithms
+
+- [ ] Bit manipulation
+- [ ] Mergesort
+- [ ] Quicksort
+- [ ] Heapsort
+- [ ] Binary search
+- [ ] Find <var>k</var>-th smallest elements
+- [ ] Permutations
+- [ ] Breadth-first search
+- [ ] Depth-first search
+- [ ] Dijkstra's algorithm
+- [ ] Tree traversal
+  - [ ] Pre-order
+  - [ ] In-order
+  - [ ] Post-order
+- [ ] Topological sort
+- [ ] Cycle detection
+  - [ ] in an undirected graph
+  - [ ] in a directed graph
+- [ ] Count connected components in a graph
+- [ ] Find strongly connected components in a graph
+
+Content
+-------

lists/LinkedList.java

@@ -0,0 +1,86 @@
+public class LinkedListNode {
+  public byte data;
+  protected LinkedListNode next;
+
+  public LinkedListNode(byte data, LinkedListNode next) {
+    this.data = data;
+    this.next = next;
+  }
+}
+
+public class LinkedList {
+  private LinkedListNode head;
+  private int length;
+
+  public LinkedList() {
+    this.head = null;
+    this.length = 0;
+  }
+
+  public LinkedListNode getHead() {
+    return this.head;
+  }
+
+  public int getLength() {
+    return this.length;
+  }
+
+  /**
+   * Insert new data at a specified index, shifting existing node at the index
+   * and all nodes after it to the right.
+   *
+   * <p>
+   * O(1) complexity for inserting at the head, O(i) complexity for other cases.
+   * @param data
+   * @param index A valid index for the new node that is between 0 and
+   * <code>this.length</code> (inclusive).
+   * @return
+  */
+  public LinkedListNode insert(byte data, int index) {
+    if (index < 0 || index > this.length) return null;
+
+    LinkedListNode newNode = new LinkedListNode(data, null);
+
+    if (index == 0) {
+      if (this.head != null) newNode.next = this.head;
+      this.head = newNode;
+
+      return newNode;
+    }
+
+    LinkedListNode prevNode = this.head;
+
+    for (int i = 1; i < index; i++)
+      prevNode = prevNode.next;
+
+    if (index != this.length)
+      newNode.next = prevNode.next;
+
+    prevNode.next = newNode;
+    this.length++;
+
+    return newNode;
+  }
+
+  /**
+   * Deletes the node at the specified index.
+   *
+   * <p>
+   * O(n) complexity
+   * @param index
+   * @return
+  */
+  public LinkedListNode delete(int index) {
+    if (index < 0 || index >= this.length || this.length == 0) return null;
+
+    LinkedListNode prevNode = this.head;
+
+    for (int i = 1; i < index; i++)
+      prevNode = prevNode.next;
+
+    LinkedListNode node = prevNode.next;
+    prevNode.next = node.next;
+
+    return node;
+  }
+}