P1-P5: rewrite to match current syllabus

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

P4.java

@@ -1,15 +1,57 @@
-class P4 {
-  public static void main(String[] _args) {
-      int n = 10;
-      int a = 0, b = 1;
-      System.out.println("First " + n + " elements of the fibonacci series:");
-      new P4().fibo(n, a, b);
-  }
+class ProducerConsumer {
+    private int limit = 5;
+    private int tmp = 0;
+    private int n = 0;
+    private int m = 0;
+    
 
-    void fibo(int n, int a, int b) {
-        if (n == 0)
-            return;
-        System.out.println(a);
-        fibo(n - 1, b, a + b);
+    public void produce() throws InterruptedException {
+        int value = 0;
+        while (n++ < limit * 2) {
+            synchronized (this) {
+                while (tmp == limit) {
+                    wait();
+                }
+                System.out.println("Producer produced: " + tmp++);
+                notify();
+            }
+        }
     }
-}
+
+    public void consume() throws InterruptedException {
+        while (m++ < limit * 2) {
+            synchronized (this) {
+                while (tmp == 0) {
+                    wait();
+                }
+                System.out.println("Consumer consumed: " + --tmp);
+                notify();
+            }
+        }
+    }
+}
+
+public class P4 {
+    public static void main(String[] args) {
+        ProducerConsumer pc = new ProducerConsumer();
+
+        Thread producerThread = new Thread(() -> {
+            try {
+                pc.produce();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+
+        Thread consumerThread = new Thread(() -> {
+            try {
+                pc.consume();
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+
+        producerThread.start();
+        consumerThread.start();
+    }
+}