implement-stack-using-queues py3

0225_implement-stack-using-queues/python3/two-queues-pop-linear.py

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+from collections import deque
+
+class MyStack:
+
+    def __init__(self):
+        self.q = deque()
+        self.tmp = deque()
+
+    def push(self, x: int) -> None:
+        self.q.append(x)
+        self.head = x
+
+    def pop(self) -> int:
+        tmp = deque()
+        popped = None
+        prev = None
+        
+        while True:
+            popped = self.q.popleft()
+            
+            if not self.q:
+                break
+            
+            prev = popped
+            tmp.append(prev)
+            
+        self.q = tmp
+        self.head = prev
+        
+        return popped
+        
+
+    def top(self) -> int:
+        return self.head
+
+    def empty(self) -> bool:
+        return len(self.q) == 0
+
+
+# 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()