Create min_stack.py

data_structures/stacks/min_stack.py

@@ -0,0 +1,83 @@
+class MinStack:
+    """ Designing a Stack that can return Minimum element in Constant time"""
+
+    def __init__(self):
+        """ Creating stack minStack and size Variable"""
+        self.stack = []
+        self.minStack = []
+        self.size = 0
+
+    def push(self, data: int) -> None:
+        """
+        Push helps to put a element a the end of the stack
+        >>> s = MinStack()
+        >>> s.push(1)
+        >>> assert s.size == 1
+        """
+        if self.size == 0:
+            self.minStack.append(data)
+        elif data <= self.minStack[-1]:
+            self.minStack.append(data)
+        self.stack.append(data)
+        self.size = self.size + 1
+
+    def pop(self) -> None:
+        """Removes the topmost element from the Stack
+        >>> s = MinStack()
+        >>> s.push(1)
+        >>> s.push(2)
+        >>> assert s.pop() == 2
+        """
+        top = self.stack.pop()
+        self.size = self.size - 1
+        if top <= self.minStack[-1]:
+            self.minStack.pop()
+        return top
+
+    def top(self) -> None:
+        """Returns the top element from the stack
+        >>> s = MinStack()
+        >>> s.push(3)
+        >>> s.push(2)
+        >>> assert s.top() == 2
+        """
+        return self.stack[-1]
+
+    def get_min(self):
+        """Returns the top element from the  Minstack
+        >>> s = MinStack()
+        >>> s.push(5)
+        >>> assert s.get_min() == 5
+        """
+        return self.minStack[-1]
+
+
+# Code execution starts here
+if __name__ == "__main__":
+
+    # Creating a min Stack
+    stack = MinStack()
+
+    stack.push(6)
+    print(stack.get_min())  # prints  6
+
+    stack.push(7)
+    print(stack.get_min())  # prints 6
+
+    stack.push(8)
+    print(stack.get_min())  # prints 6
+
+    stack.push(5)
+    print(stack.get_min())  # prints 5
+
+    stack.push(3)
+    print(stack.get_min())  # prints 3
+
+    stack.pop()
+    print(stack.get_min())  # prints 5
+
+    stack.push(10)
+    print(stack.get_min())  # prints 5
+
+    stack.pop()
+    print(stack.get_min())  # prints 5