定义栈的数据结构，请在该类型中实现一个能够得到栈中所含最小元素的min函数（时间复杂度应为O（1））。
import java.util.Stack;
public class Solution {
Stack<Integer> stack = new Stack<Integer>();
public void push(int node) {
stack.push(node);
}
public void pop() {
stack.pop();
}
public int top() {
return stack.peek();
}
public int min() {
Stack<Integer> temp = new Stack<Integer>();
int min = Integer.MAX_VALUE;
while(!stack.isEmpty()) {
int top = stack.pop();;
if(min > top) {
min = top;
}
temp.push(top);
}
while(!temp.isEmpty()) {
stack.push(temp.pop());
}
return min;
}
}
