Completed pr1

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "java.debug.settings.onBuildFailureProceed": true
+}

Exercise_1.java

@@ -7,29 +7,54 @@ class Stack {
 
     boolean isEmpty() 
     { 
-        //Write your code here 
+        return top == -1;
     } 
 
     Stack() 
     { 
-        //Initialize your constructor 
+       top = -1;
+
     } 
 
     boolean push(int x) 
     { 
         //Check for stack Overflow
         //Write your code here
+        if(top>= MAX-1){
+            System.out.println("stack is overflow");
+            return false; 
+        }
+        else{
+            a[++top] = x;
+
+     return true;
+        }
     } 
 
     int pop() 
     { 
         //If empty return 0 and print " Stack Underflow"
         //Write your code here
+        if(isEmpty()){
+          System.out.println("stack is empty"); 
+          return 0; 
+        }
+        else{
+            return a[top--];
+        }
     } 
 
     int peek() 
     { 
         //Write your code here
+        if(isEmpty()){
+          System.out.println("stack is empty");  
+          return 0;
+        }
+        else{
+            return a[top];
+
+        }
     } 
 } 
 

Exercise_3.java → LinkedList.java

@@ -15,36 +15,50 @@ static class Node {
         Node next; 
 
         // Constructor 
-        Node(int d) 
-        { 
-            //Write your code here 
+        Node(int d) { 
+            this.data = d;
+            this.next = null;
         } 
     } 
 
     // Method to insert a new node 
     public static LinkedList insert(LinkedList list, int data) 
     { 
-        // Create a new node with given data 
-   
+        Node newNode = new Node(data);
+
         // If the Linked List is empty, 
-        // then make the new node as head 
-
+        // then make the new node as head
+        if (list.head == null) { 
+            list.head = newNode; 
+        } else { 
             // Else traverse till the last node 
-            // and insert the new_node there 
-
+            // and insert the new_node there
+            Node last = list.head; 
+            while (last.next != null) { 
+                last = last.next; 
+            } 
+
             // Insert the new_node at last node 
-        // Return the list by head 
-
+            last.next = newNode; 
+        } 
+
+        // Return the list by head
+        return list; 
     } 
 
     // Method to print the LinkedList. 
     public static void printList(LinkedList list) 
     {  
+        Node currentNode = list.head; 
+
         // Traverse through the LinkedList 
-
-            // Print the data at current node 
-
-            // Go to next node 
+        while (currentNode != null) { 
+            // Print the data at current node
+            System.out.print(currentNode.data + " "); 
+
+            // Go to the next node
+            currentNode = currentNode.next; 
+        } 
     } 
 
     // Driver code 

StackAsLinkedList.java

@@ -0,0 +1,68 @@
+public class StackAsLinkedList { 
+
+    StackNode root;
+
+    static class StackNode { 
+        int data; 
+        StackNode next; 
+
+        StackNode(int data) 
+        { 
+            //Constructor here 
+            this.data = data;
+            this.next = null;
+        } 
+    } 
+
+
+    public boolean isEmpty() 
+    { 
+        //Write your code here for the condition if stack is empty. 
+        return root == null;
+    } 
+
+    public void push(int data) 
+    { 
+        StackNode newNode = new StackNode(data);
+        newNode.next = root;  // Link the new node to the current root
+        root = newNode; 
+    } 
+
+    public int pop() 
+    { 	
+        if (isEmpty()) {
+            System.out.println("Stack Underflow");
+            return 0;
+        }
+
+        // Pop the topmost element
+        int poppedData = root.data;  // Store data of the top node
+        root = root.next;            // Move root to the next node
+        return poppedData; 
+    } 
+
+    public int peek() 
+    { 
+        if (isEmpty()) {
+            System.out.println("Stack is empty");
+            return 0;
+        }
+
+        // Return the topmost element without removing it
+        return root.data;
+    }
+	//Driver code
+    public static void main(String[] args) 
+    { 
+
+        StackAsLinkedList sll = new StackAsLinkedList(); 
+
+        sll.push(10); 
+        sll.push(20); 
+        sll.push(30); 
+
+        System.out.println(sll.pop() + " popped from stack"); 
+
+        System.out.println("Top element is " + sll.peek()); 
+    } 
+}