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MyQueue queue = new MyQueue();
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queue.push(1);
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queue.push(2);
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queue.peek();  // returns 1
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queue.pop();   // returns 1
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queue.empty(); // returns false

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# @Author：Kilien
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# @lc app=leetcode id=232 lang=python3
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# [232] Implement Queue using Stacks
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# time:O(1) space:O(n)
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#思路：两个数组，模拟入栈出栈，实现队列；具体见图解
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class MyQueue:
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    def __init__(self):
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        """
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        initialize your data structure here.
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        """
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        self.inStack, self.outStack = [], []
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    def push(self, x):
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        """
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        :type x: int
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        :rtype: nothing
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        """
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        self.inStack.append(x)
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    def pop(self):
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        """
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        :rtype: nothing
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        """
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        self.move()
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        return self.outStack.pop()
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    def peek(self):
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        """
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        :rtype: int
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        """
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        self.move()
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        return self.outStack[-1]
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    def empty(self):
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        """
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        :rtype: bool
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        """
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        return (not self.inStack) and (not self.outStack)
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    def move(self):
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        """
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        :rtype nothing
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        """
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        if not self.outStack:
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            while self.inStack:
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                self.outStack.append(self.inStack.pop())
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# Your MyQueue object will be instantiated and called as such:
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# obj = MyQueue()
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# obj.push(x)
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# param_2 = obj.pop()
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# param_3 = obj.peek()
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# param_4 = obj.empty()