Solved implement-stack-using-queues using python3

Python/implement-stack-using-queues.py

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+"""
+Problem Statement : 
+
+Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty).
+
+Implement the MyStack class:
+
+void push(int x) Pushes element x to the top of the stack.
+int pop() Removes the element on the top of the stack and returns it.
+int top() Returns the element on the top of the stack.
+boolean empty() Returns true if the stack is empty, false otherwise.
+Notes:
+
+You must use only standard operations of a queue, which means that only push to back, peek/pop from front, size and is empty operations are valid.
+Depending on your language, the queue may not be supported natively. You may simulate a queue using a list or deque (double-ended queue) as long as you use only a queue's standard operations.
+
+"""
+
+#Solution using collections 
+import collections 
+
+class MyStack:
+
+ def __init__(self):
+ self._queue = collections.deque()
+
+ def push(self, x):
+ q = self._queue
+ q.append(x)
+ for _ in range(len(q) - 1):
+ q.append(q.popleft())
+
+ def pop(self):
+ return self._queue.popleft()
+
+ def top(self):
+ return self._queue[0]
+
+ def empty(self):
+ return not len(self._queue)
+
+# Your MyStack object will be instantiated and called as such:
+# obj = MyStack()
+# obj.push(x)
+# param_2 = obj.pop()
+# param_3 = obj.top()
+# param_4 = obj.empty()