Implemented solutions for questions 1-3

solution.py

@@ -0,0 +1,86 @@
+##1. Reverse String
+def reverse_string(s: str) -> str:
+    stack = []
+    # Push all characters of the string onto the stack
+    for char in s:
+        stack.append(char)
+
+    # Pop characters from the stack to reverse the string
+    reversed_str = ""
+    while stack:
+        reversed_str += stack.pop()
+
+    return reversed_str
+
+# Example Usage:
+print(reverse_string("hello"))  # Output: "olleh"
+
+##2. Implement a Queue Using Two Stacks
+class QueueWithStacks:
+    def __init__(self):
+        self.stack1 = []
+        self.stack2 = []
+
+    def enqueue(self, x: int):
+        # Push element onto stack1
+        self.stack1.append(x)
+
+    def dequeue(self) -> int:
+        # If stack2 is empty, move all elements from stack1 to stack2
+        if not self.stack2:
+            while self.stack1:
+                self.stack2.append(self.stack1.pop())
+
+        # Pop the top element from stack2
+        if self.stack2:
+            return self.stack2.pop()
+        else:
+            return None  # Queue is empty
+
+# Example Usage:
+q = QueueWithStacks()
+q.enqueue(1)
+q.enqueue(2)
+print(q.dequeue())  # Output: 1
+print(q.dequeue())  # Output: 2
+
+##3. class Node
+def __init__(self, data):
+        self.data = data
+        self.next = None
+
+class LinkedList:
+    def __init__(self):
+        self.head = None
+
+    def append(self, data):
+        new_node = Node(data)
+        if not self.head:
+            self.head = new_node
+            return
+        last = self.head
+        while last.next:
+            last = last.next
+        last.next = new_node
+
+    def find_max(self) -> int:
+        if not self.head:
+            return None  # List is empty
+
+        max_val = self.head.data
+        current = self.head
+        while current:
+            if current.data > max_val:
+                max_val = current.data
+            current = current.next
+
+        return max_val
+
+# Example Usage:
+ll = LinkedList()
+ll.append(3)
+ll.append(1)
+ll.append(4)
+ll.append(2)
+print(ll.find_max())  # Output: 4
+