demo1.txt

package chapter1;

import java.util.Iterator;
import java.util.Stack;
//我用了迭代器的方法，不过确实复杂度是书上的低一点，只不过空间复杂度这里低点
public class demo1 {

	public static Stack<Integer> stack1;
	public static Stack<Integer> stack2;
	
	public static void main(String[] args) {
		 stack1 = new Stack<Integer>();
		 stack2 = new Stack<Integer>();
		 demo1 my = new demo1();
		 my.push(2);
		 my.push(6);
		 my.push(1);
		 my.push(9);
		 System.out.println(my.getMin());
	}

	//插入数据push
	public  void push(int a){
		stack1.push(a);  
		
		if(stack2.isEmpty()){
			stack2.push(a);
		}
		else{
			if(stack2.peek()>a){
				stack2.push(a);
			}
		}
	}
	
	//pop
	public  int pop(){
		int value = stack1.pop();
		if(!stack2.isEmpty() && value==stack2.peek()){
			stack2.pop();
		}
		return value;
	}

	public  int getMin(){
		int value1 = stack2.pop();
		if(!stack1.isEmpty()&&stack1.peek()==value1){
			stack1.pop();
		}
		return value1;
	}
	
	/*	
	//获取最小值
	public static int getMin(){
		//可以对栈进行迭代遍历吧
		Iterator<Integer> it = stack1.iterator();
		int min = stack1.peek();
		while(it.hasNext()){
			int temp = it.next();
			if(min>temp){
				min = temp;
			}
		}
		return min;
	}
	*/
	
	
	
}