Learning On the Way

232. Implement Queue using Stacks

class MyQueue: 
    def __init__(self): 
        self.primary = [] 
        self.secondary = [] 
        self._front = None 
         
    def push(self, x: int) -> None: 
        self.primary.append(x)

    def pop(self) -> int: 
        self.peek() 
        return self.secondary.pop() 
     
    def peek(self) -> int: 
        if not self.secondary: 
            while self.primary: 
                self.secondary.append(self.primary.pop()) 
        return self.secondary[-1] 
        
    def empty(self) -> bool: 
        return not self.primary and not self.secondary