Create stack.py

Author: rvyash

stack.py

@@ -0,0 +1,56 @@
+# Python program to reverse a string using stack 
+
+# Function to create an empty stack. 
+# It initializes size of stack as 0 
+def createStack(): 
+	stack=[] 
+	return stack 
+
+# Function to determine the size of the stack 
+def size(stack): 
+	return len(stack) 
+
+# Stack is empty if the size is 0 
+def isEmpty(stack): 
+	if size(stack) == 0: 
+		return true 
+
+# Function to add an item to stack . 
+# It increases size by 1 
+def push(stack,item): 
+	stack.append(item) 
+
+#Function to remove an item from stack. 
+# It decreases size by 1 
+def pop(stack): 
+	if isEmpty(stack): return
+	return stack.pop() 
+
+# A stack based function to reverse a string 
+def reverse(string): 
+	n = len(string) 
+	
+	# Create a empty stack 
+	stack = createStack() 
+
+	# Push all characters of string to stack 
+	for i in range(0,n,1): 
+		push(stack,string[i]) 
+
+	# Making the string empty since all 
+	#characters are saved in stack 
+	string="" 
+
+	# Pop all characters of string and 
+	# put them back to string 
+	for i in range(0,n,1): 
+		string+=pop(stack) 
+		
+	return string 
+	
+# Driver program to test above functions 
+string="GeeksQuiz"
+string = reverse(string) 
+print("Reversed string is " + string) 
+
+# This code is contributed by Yash