Create Stack.py

Author: dipta-dhar

DataStructure/Stack.py

@@ -0,0 +1,43 @@
+class StackNode:
+ 
+    # Constructor to initialize a node
+    def __init__(self, data):
+        self.data = data 
+        self.next = None
+ 
+class Stack:
+     
+    # Constructor to initialize the root of linked list
+    def __init__(self):
+        self.root = None
+ 
+    def isEmpty(self):
+        return True if self.root is None else  False
+ 
+    def push(self, data):
+        newNode = StackNode(data)
+        newNode.next = self.root 
+        self.root = newNode
+        print "%d pushed to stack" %(data)
+     
+    def pop(self):
+        if (self.isEmpty()):
+            return float("-inf")
+        temp = self.root 
+        self.root = self.root.next
+        popped = temp.data
+        return popped
+     
+    def peek(self):
+        if self.isEmpty():
+            return float("-inf")
+        return self.root.data
+ 
+# Driver program to test above class 
+stack = Stack()
+stack.push(10)        
+stack.push(20)
+stack.push(30)
+ 
+print "%d popped from stack" %(stack.pop())
+print "Top element is %d " %(stack.peek())