用两个栈实现队列
Question
用两个栈来实现一个队列，完成队列的Push和Pop操作。 队列中的元素为int类型。
Answer
package queuebystack;
import java.util.Stack;
public class QueueByStack {
Stack<Integer> stack1 = new Stack<>();
Stack<Integer> stack2 = new Stack<>();
private void move(Stack<Integer> source, Stack<Integer> target) {
while(!source.isEmpty()) {
target.push(source.pop());
}
}
public void enqueue(int node) {
if(stack1.isEmpty()) {
move(stack2, stack1);
}
stack1.push(node);
}
public int dequeue() {
if(stack2.isEmpty()) {
move(stack1, stack2);
}
return stack2.pop();
}
public static void main(String[] args) {
// TODO Auto-generated method stub
QueueByStack obj = new QueueByStack();
obj.enqueue(1);
obj.enqueue(2);
obj.enqueue(3);
obj.enqueue(4);
obj.enqueue(5);
System.out.println(obj.dequeue());
System.out.println(obj.dequeue());
System.out.println(obj.dequeue());
System.out.println(obj.dequeue());
}
}
