LintCode 40 · Implement Queue by Two Stacks.java

	public class MyQueue {
	Stack<Integer> stack = new Stack<>();
	Stack<Integer> stack2 = new Stack<>();
	public MyQueue() {
	// do intialization if necessary
	stack = new Stack<>();
	stack2 = new Stack<>();
	}
	/*
	* @param element: An integer
	* @return: nothing
	*/
	public void push(int element) {
	// write your code here
	stack.push(element);
	}
	/*
	* @return: An integer
	*/
	public int pop() {
	// write your code here
	if (stack2.isEmpty()) {
	while (!stack.isEmpty()) {
	stack2.push(stack.pop());
	}
	}
	return stack2.pop();
	}
	/*
	* @return: An integer
	*/
	public int top() {
	// write your code here
	if (stack2.isEmpty()) {
	while (!stack.isEmpty()) {
	stack2.push(stack.pop());
	}
	}
	return stack2.peek();
	}
	}

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