diff --git a/Exercise_1.cpp b/Exercise_1.cpp
index 381e274d5..181a8eecb 100644
--- a/Exercise_1.cpp
+++ b/Exercise_1.cpp
@@ -1,54 +1,101 @@
-#include <bits/stdc++.h> 
-  
-using namespace std; 
-  
-#define MAX 1000 
-  
-class Stack {
-  //Please read sample.java file before starting.
-  //Kindly include Time and Space complexity at top of each file
-    int top; 
-  
-public: 
-    int a[MAX]; // Maximum size of Stack 
-  
-    Stack() { //Constructor here } 
-    bool push(int x); 
-    int pop(); 
-    int peek(); 
-    bool isEmpty(); 
-}; 
-  
-bool Stack::push(int x) 
-{ 
-    //Your code here
-    //Check Stack overflow as well
-} 
-  
-int Stack::pop() 
-{ 
-    //Your code here
-    //Check Stack Underflow as well 
-} 
-int Stack::peek() 
-{ 
-    //Your code here
-    //Check empty condition too
-} 
-  
-bool Stack::isEmpty() 
-{ 
-    //Your code here 
-} 
-  
-// Driver program to test above functions 
-int main() 
-{ 
-    class Stack s; 
-    s.push(10); 
-    s.push(20); 
-    s.push(30); 
-    cout << s.pop() << " Popped from stack\n"; 
-  
-    return 0; 
-} 
+#include <bits/stdc++.h>
+
+using namespace std;
+
+#define MAX 1000
+
+/*
+Time Complexity :
+    push(): O(1)
+    pop(): O(1)
+    peek(): O(1)
+    isEmpty(): O(1)
+
+Space Complexity :
+    stack: O(n), n is number of elements in stack
+
+Did this code successfully run on Leetcode : Couldn't find the leetcode problem
+
+Any problem you faced while coding this : None
+*/
+class Stack
+{
+    int top;
+
+public:
+    int a[MAX]; // Maximum size of Stack
+
+    Stack()
+    {
+        top = -1;
+    }
+    bool push(int x);
+    int pop();
+    int peek();
+    bool isEmpty();
+};
+
+// Push data onto the stack
+bool Stack::push(int x)
+{
+    if (top >= MAX)
+    {
+        return false;
+    }
+
+    a[++top] = x;
+
+    return true;
+}
+
+// Pop data from the stack
+int Stack::pop()
+{
+    if (isEmpty())
+    {
+        return -1;
+    }
+    else
+    {
+        return a[top--];
+    }
+}
+
+// Peek the top element of the stack
+int Stack::peek()
+{
+    if (isEmpty())
+    {
+        return -1;
+    }
+
+    return a[top];
+}
+
+// Check if the stack is empty
+bool Stack::isEmpty()
+{
+    if (top < 0)
+    {
+        return true;
+    }
+
+    return false;
+}
+
+// Driver program to test above functions
+int main()
+{
+    class Stack s;
+    s.push(10);
+    s.push(20);
+    s.push(30);
+    cout << s.peek() << " Peeked from stack\n";
+    cout << s.pop() << " Popped from stack\n";
+    cout << s.peek() << " Peeked from stack\n";
+    cout << s.pop() << " Popped from stack\n";
+    cout << s.peek() << " Peeked from stack\n";
+    cout << s.pop() << " Popped from stack\n";
+
+    return 0;
+}
diff --git a/Exercise_2.cpp b/Exercise_2.cpp
index 1eb3de9b9..704c2806a 100644
--- a/Exercise_2.cpp
+++ b/Exercise_2.cpp
@@ -1,52 +1,100 @@
-#include <bits/stdc++.h> 
-using namespace std; 
-  
-// A structure to represent a stack 
-class StackNode { 
-public: 
-    int data; 
-    StackNode* next; 
-}; 
-  
-StackNode* newNode(int data) 
-{ 
-    StackNode* stackNode = new StackNode(); 
-    stackNode->data = data; 
-    stackNode->next = NULL; 
-    return stackNode; 
-} 
-  
-int isEmpty(StackNode* root) 
-{ 
-    //Your code here 
-} 
-  
-void push(StackNode** root, int data) 
-{ 
-    //Your code here 
-} 
-  
-int pop(StackNode** root) 
-{ 
-    //Your code here 
-} 
-  
-int peek(StackNode* root) 
-{ 
-    //Your code here 
-} 
-  
-int main() 
-{ 
-    StackNode* root = NULL; 
-  
-    push(&root, 10); 
-    push(&root, 20); 
-    push(&root, 30); 
-  
-    cout << pop(&root) << " popped from stack\n"; 
-  
-    cout << "Top element is " << peek(root) << endl; 
-  
-    return 0; 
-} 
\ No newline at end of file
+#include <bits/stdc++.h>
+using namespace std;
+
+/*
+Time Complexity :
+    push(): O(1)
+    pop(): O(1)
+    peek(): O(1)
+    isEmpty(): O(1)
+
+Space Complexity :
+    stack: O(n), n is number of elements in the stack
+
+Did this code successfully run on Leetcode : Couldn't find the leetcode problem
+
+Any problem you faced while coding this : None
+*/
+
+// A structure to represent a stack
+class StackNode
+{
+public:
+    int data;
+    StackNode *next;
+};
+
+StackNode *newNode(int data)
+{
+    StackNode *stackNode = new StackNode();
+    stackNode->data = data;
+    stackNode->next = NULL;
+    return stackNode;
+}
+
+// Check if the stack is empty
+int isEmpty(StackNode *root)
+{
+    return root == NULL;
+}
+
+// Push data onto the stack
+void push(StackNode **root, int data)
+{
+    StackNode *node = newNode(data);
+
+    node->next = *root;
+
+    *root = node;
+}
+
+// Pop data from the stack
+int pop(StackNode **root)
+{
+    if (isEmpty(*root))
+    {
+        return -1;
+    }
+
+    StackNode *node = *root;
+    
+    *root = (*root)->next;
+    
+    int popped = node->data;
+    
+    delete node; // Free memory to prevent memory leaks
+    
+    return popped;
+}
+
+// Peek the top element of the stack
+int peek(StackNode *root)
+{
+    if (isEmpty(root))
+    {
+        return -1;
+    }
+
+    return root->data;
+}
+
+int main()
+{
+    StackNode *root = NULL;
+
+    push(&root, 10);
+    push(&root, 20);
+    push(&root, 30);
+
+    cout << pop(&root) << " popped from stack\n";
+
+    cout << "Top element is " << peek(root) << endl;
+
+    cout << pop(&root) << " popped from stack\n";
+
+    cout << "Top element is " << peek(root) << endl;
+
+    cout << pop(&root) << " popped from stack\n";
+
+    return 0;
+}
\ No newline at end of file
diff --git a/Exercise_3.cpp b/Exercise_3.cpp
index f34d89ac1..7121d3b42 100644
--- a/Exercise_3.cpp
+++ b/Exercise_3.cpp
@@ -1,80 +1,116 @@
-#include <bits/stdc++.h> 
-using namespace std; 
-  
-// A linked list node (changes) 
-class Node  
-{  
-    public: 
-    int data;  
-    Node *next;  
-};  
-  
-/* Given a reference (pointer to pointer) 
-to the head of a list and an int, inserts 
+#include <bits/stdc++.h>
+using namespace std;
+
+/*
+Time Complexity :
+    push(): O(1)
+    insertAfter(): O(1)
+    append(): O(n), n is the number of elements in the list
+    printList(): O(n), n is the number of elements in the list
+
+Space Complexity :
+    linked list: O(n), n is number of elements in list
+
+Did this code successfully run on Leetcode : Couldn't find the leetcode problem
+
+Any problem you faced while coding this : None
+*/
+
+// A linked list node (changes)
+class Node
+{
+public:
+    int data;
+    Node *next;
+};
+
+/* Given a reference (pointer to pointer)
+to the head of a list and an int, inserts
 a new node on the front of the list. */
-void push(Node** head_ref, int new_data)  
-{  
-    /* 1. allocate node */ 
-  
-    /* 2. put in the data */  
-  
-    /* 3. Make next of new node as head */ 
-  
+void push(Node** head_ref, int new_data)
+{
+    /* 1. allocate node */
+    Node* node = new Node();
+
+    /* 2. put in the data */
+    node->data = new_data;
+    /* 3. Make next of new node as head */
+    node->next = *head_ref;
     /* 4. move the head to point to the new node */
-}  
-  
-/* Given a node prev_node, insert a new node after the given  
+    *head_ref = node;
+}
+
+/* Given a node prev_node, insert a new node after the given
 prev_node */
-void insertAfter(Node* prev_node, int new_data)  
-{  
-    /*1. check if the given prev_node is NULL */ 
-  
-    /* 2. allocate new node */ 
-  
-    /* 3. put in the data */ 
-  
+void insertAfter(Node* prev_node, int new_data)
+{
+    /*1. check if the given prev_node is NULL */
+    if (prev_node == NULL)
+    {
+        return;
+    }
+    /* 2. allocate new node */
+    Node *node = new Node();
+    /* 3. put in the data */
+    node->data = new_data;
     /* 4. Make next of new node as next of prev_node */
-  
-    /* 5. move the next of prev_node as new_node */ 
-}  
-  
-/* Given a reference (pointer to pointer) to the head  
+    node->next = prev_node->next;
+    /* 5. move the next of prev_node as new_node */
+    prev_node->next = node;
+}
+
+/* Given a reference (pointer to pointer) to the head
 of a list and an int, appends a new node at the end */
-void append(Node** head_ref, int new_data)  
-{  
-    /* 1. allocate node */ 
-  
-    /* 2. put in the data */ 
-  
-    /* 3. This new node is going to be  
-    the last node, so make next of  
-    it as NULL*/  
-  
-    /* 4. If the Linked List is empty, 
+void append(Node** head_ref, int new_data)
+{
+    /* 1. allocate node */
+    Node *node = new Node();
+    /* 2. put in the data */
+    node->data = new_data;
+    /* 3. This new node is going to be
+    the last node, so make next of
+    it as NULL*/
+    node->next = NULL;
+    /* 4. If the Linked List is empty,
     then make the new node as head */
-  
+    if (*head_ref == NULL)
+    {
+        *head_ref = node;
+        return;
+    }
     /* 5. Else traverse till the last node */
-  
-    /* 6. Change the next of last node */ 
-}  
-  
-// This function prints contents of 
-// linked list starting from head  
-void printList(Node *node)  
-{  
-    //Your code here
-}  
-  
+    Node *iter = *head_ref;
+
+    while (iter->next != NULL)
+    {
+        iter = iter->next;
+    }
+
+    /* 6. Change the next of last node */
+    iter->next = node;
+}
+
+// This function prints contents of
+// linked list starting from head
+void printList(Node *node)
+{
+    while (node != NULL)
+    {
+        cout << node->data << endl;
+        node = node->next;
+    }
+}
+
 /* Driver code*/
-int main()  
-{  
-    Node* head = NULL;   
-    append(&head, 6);  
-    push(&head, 7);  
-    push(&head, 1);    
-    append(&head, 4);    
-    insertAfter(head->next, 8);  
-    cout<<"Created Linked list is: ";  
-    printList(head);  
-    return 0;  
-}  
\ No newline at end of file
+int main()
+{
+    Node* head = NULL;
+    append(&head, 6);
+    push(&head, 7);
+    push(&head, 1);
+    append(&head, 4);
+    insertAfter(head->next, 8);
+    cout<<"Created Linked list is: ";
+    printList(head);
+    return 0;
+}
\ No newline at end of file