algorithms lesson #7

Author: biblelamp

BerlinTelran/Algorithms/src/lesson7/DynamiListDemo.java

@@ -1,2 +1,20 @@
-package lesson7;public class DynamiListDemo {
+package lesson7;
+
+public class DynamiListDemo {
+    public static void main(String[] args) {
+        DynamicList dynamicList = new DynamicList();
+        dynamicList.push(12);
+        dynamicList.push(8);
+        dynamicList.push(5);
+        dynamicList.push(2);
+        System.out.println(dynamicList);
+        for (int i = 0; i < 5; i++) {
+            System.out.println(dynamicList.pop() + " <- " + dynamicList);
+        }
+        dynamicList.offer(12);
+        dynamicList.offer(8);
+        dynamicList.offer(5);
+        dynamicList.offer(2);
+        System.out.println(dynamicList);
+    }
 }

BerlinTelran/Algorithms/src/lesson7/DynamicList.java

@@ -1,2 +1,83 @@
-package lesson7;public class DynamicList {
+package lesson7;
+
+public class DynamicList {
+    private int size;
+    private Node first;
+    private Node last;
+
+    public void push(Integer value) {
+        if (first == null) { // push 1st element
+            first = new Node(value, null, null);
+        } else if (last == null) { // push 2nd element
+            last = first;
+            first = new Node(value, null, last);
+            first.pred = first;
+            last.pred = first;
+        } else { // push 3rd and other(s)
+            Node newFirst = new Node(value, null, first);
+            first.pred = newFirst;
+            first = newFirst;
+        }
+        size++;
+    }
+
+    public void offer(Integer value) {
+        if (first == null) { // offer 1st element
+            first = new Node(value, null, null);
+        }  else if (last == null) { // offer 2nd element
+            last = new Node(value, first, null);
+            first.next = last;
+        } else { // offer 3rd and other(s)
+            Node newLast = new Node(value, last, null);
+            last.next = newLast;
+            last = newLast;
+        }
+        size++;
+    }
+
+    // TODO implement poll()
+
+    public Integer pop() {
+        Integer value = null;
+        if (first != null) {
+            value = first.value;
+            first = first.next;
+            if (first != null) {
+                first.pred = null;
+                if (first.next == null) {
+                    last = null;
+                }
+            }
+            size--;
+        }
+        return value;
+    }
+
+    @Override
+    public String toString() {
+        StringBuffer sb = new StringBuffer("[");
+        if (first != null) {
+            Node cursor = first;
+            do {
+                sb.append(cursor.value);
+                cursor = cursor.next;
+                if (cursor != null) {
+                    sb.append(", ");
+                }
+            } while (cursor != null);
+        }
+        return sb.append("]").toString();
+    }
+
+    private class Node {
+        Integer value;
+        Node pred;
+        Node next;
+
+        public Node(Integer value, Node pred, Node next) {
+            this.value = value;
+            this.pred = pred;
+            this.next = next;
+        }
+    }
 }

BerlinTelran/Algorithms/src/lesson7/Lesson7.java

@@ -1,2 +1,36 @@
-package lesson7;public class Lesson7 {
+package lesson7;
+
+import java.util.LinkedList;
+
+/**
+ * Algorithms. Lesson #7. Stack and Queue
+ *
+ * @author Sergey Iryupin
+ * @version 11 Aug 2023
+ */
+
+public class Lesson7 {
+    public static void main(String[] args) {
+        LinkedList<Integer> stackQueue = new LinkedList<>();
+        // LinkedList like Stack
+        stackQueue.push(5);
+        System.out.println(stackQueue);
+        stackQueue.push(12);
+        System.out.println(stackQueue);
+        stackQueue.push(-2);
+        System.out.println("like Stack: " + stackQueue);
+        for (int i = 0; i < 3; i++) {
+            System.out.println(stackQueue.pop() + " <- " + stackQueue);
+        }
+        // LinkedList like Queue
+        stackQueue.offer(8);
+        System.out.println(stackQueue);
+        stackQueue.offer(-5);
+        System.out.println(stackQueue);
+        stackQueue.offer(11);
+        System.out.println("like Queue: " + stackQueue);
+        for (int i = 0; i < 3; i++) {
+            System.out.println(stackQueue.poll() + " <- " + stackQueue);
+        }
+    }
 }