Stack node implementation

bfs.java → data_structures/Graphs/bfs.java

@@ -2,56 +2,56 @@
 
 /**
  * Implementation of a Breadth First Search
- * 
+ *
  * @author Unknown
  *
  */
 public class bfs{
-	
+
 	/**
-	 * The BFS implemented in code to use. 
-	 * 
-	 * @param a Structure to perform the search on
+	 * The BFS implemented in code to use.
+	 *
+	 * @param a Structure to perform the search on a graph, adjacency matrix etc.
 	 * @param vertices The vertices to use
 	 * @param source The Source
 	 */
 	public static void bfsImplement(byte [][] a,int vertices,int source){  //passing adjacency matrix and no of vertices
 		byte []b=new byte[vertices];    //flag container containing status of each vertices
 		Arrays.fill(b,(byte)-1);   //status initialization
-		/*       code   status 
+		/*       code   status
 				 -1  =  ready
 				  0  =  waiting
 				  1  =  processed       */
-				
+
 		Stack st = new Stack(vertices);     //operational stack
 		st.push(source);                                                 //assigning source
 		while(!st.isEmpty()){
 			b[st.peek()]=(byte)0;                                   //assigning waiting status
 			System.out.println(st.peek());
 			int pop=st.peek();
 			b[pop]=(byte)1;               //assigning processed status
-			st.pop();                  //removing head of the queue 
+			st.pop();                  //removing head of the queue
 			for(int i=0;i<vertices;i++){
 				if(a[pop][i]!=0 && b[i]!=(byte)0 && b[i]!=(byte)1 ){
 					st.push(i);
 					b[i]=(byte)0;                        //assigning waiting status
 				}}}
 	}
-	
-	
+
+
 	/**
-	 * The main method 
-	 * 
+	 * The main method
+	 *
 	 * @param args Command line arguments
 	 */
 		public static void main(String args[]){
 		Scanner in=new Scanner(System.in);
 		int vertices=in.nextInt(),source=in.nextInt();
 		byte [][]a=new byte [vertices][vertices];
 		//initially all elements of a are initialized with value zero
-		
+
 		for(int i=0;i<vertices;i++){
-			int size =in.nextInt(); 
+			int size =in.nextInt();
 			for(int j=0;j<size;j++){
 				a[i][in.nextInt()]=1;      //taking adjacency entries by assigning 1
 			}

data_structures/Stacks/NodeStack.java

@@ -0,0 +1,183 @@
+/**
+* Implementation of a stack using nodes.
+* Unlimited size, no arraylist.
+*
+* @author Kyler Smith, 2017
+*/
+
+
+public class NodeStack<Item> {
+
+    /**
+    * Entry point for the program.
+    */
+    public static void main(String[] args) {
+        NodeStack<Integer> Stack = new NodeStack<Integer>();
+
+        Stack.push(3);
+        Stack.push(4);
+        Stack.push(5);
+        System.out.println("Testing :");
+        Stack.print();  			// prints : 5 4 3
+
+        Integer x = Stack.pop(); 	// x = 5
+        Stack.push(1);
+        Stack.push(8);
+        Integer y = Stack.peek();	// y = 8
+        System.out.println("Testing :");
+        Stack.print();				// prints : 8 1 4 3
+
+        System.out.println("Testing :");
+        System.out.println("x : " + x);
+        System.out.println("y : " + y);
+    }
+
+    /**
+    * Information each node should contain.
+    * @value data : information of the value in the node
+    * @value head : the head of the stack
+    * @value next : the next value from this node
+    * @value previous : the last value from this node
+    * @value size : size of the stack
+    */
+    private Item data;
+    private static NodeStack<?> head;
+    private NodeStack<?> next;
+    private NodeStack<?> previous;
+    private static int size = 0;
+
+
+    /**
+    * Constructors for the NodeStack.
+    */
+    public NodeStack() {
+	}
+
+    private NodeStack(Item item) {
+        this.data = item;
+    }
+
+    /**
+    * Put a value onto the stack.
+    *
+    * @param item : value to be put on the stack.
+    */
+    public void push(Item item) {
+
+    	NodeStack<Item> newNs = new NodeStack<Item>(item);
+
+        if(this.isEmpty()) {
+        	NodeStack.setHead(new NodeStack<>(item));
+        	newNs.setNext(null);
+        	newNs.setPrevious(null);
+        } else {
+        	newNs.setPrevious(NodeStack.head);
+        	NodeStack.head.setNext(newNs);
+        	NodeStack.head = newNs;
+        }
+
+        NodeStack.setSize(NodeStack.getSize() + 1);
+    }
+
+    /**
+    * Value to be taken off the stack.
+    *
+    * @return item : value that is returned.
+    */
+    public Item pop() {
+
+    	Item item = (Item) NodeStack.head.getData();
+
+    	NodeStack.head = NodeStack.head.getPrevious();
+    	NodeStack.head.setNext(null);
+
+    	NodeStack.setSize(NodeStack.getSize() - 1);
+
+        return item;
+    }
+
+    /**
+    * Value that is next to be taken off the stack.
+    *
+    * @return item : the next value that would be popped off the stack.
+    */
+    public Item peek() {
+        return (Item) NodeStack.head.getData();
+    }
+
+    /**
+    * If the stack is empty or there is a value in.
+    *
+    * @return boolean : whether or not the stack has anything in it.
+    */
+    public boolean isEmpty() {
+        return NodeStack.getSize() == 0;
+    }
+
+    /**
+    * Returns the size of the stack.
+    *
+    * @return int : number of values in the stack.
+    */
+    public int size() {
+        return NodeStack.getSize();
+    }
+
+    /**
+    * Print the contents of the stack in the following format.
+    *
+    * x <- head (next out)
+    * y
+    * z <- tail (first in)
+    * .
+    * .
+    * .
+    *
+    */
+    public void print() {
+    	for(NodeStack<?> n = NodeStack.head; n != null; n = n.previous) {
+    		System.out.println(n.getData().toString());
+    	}
+    }
+
+    /** Getters and setters (private) */
+    private NodeStack<?> getHead() {
+    	return NodeStack.head;
+    }
+
+    private static void setHead(NodeStack<?> ns) {
+    	NodeStack.head = ns;
+    }
+
+    private NodeStack<?> getNext() {
+		return next;
+	}
+
+    private void setNext(NodeStack<?> next) {
+		this.next = next;
+	}
+
+    private NodeStack<?> getPrevious() {
+		return previous;
+	}
+
+    private void setPrevious(NodeStack<?> previous) {
+		this.previous = previous;
+	}
+
+    private static int getSize() {
+		return size;
+	}
+
+    private static void setSize(int size) {
+		NodeStack.size = size;
+	}
+
+    private Item getData() {
+		return this.data;
+	}
+
+    private void setData(Item item) {
+		this.data = item;
+	}
+}