Stack<Integer> mData=http://www.mamicode.com/new Stack<Integer>();
    Stack<Integer> mMin=new Stack<Integer>();
    //java中的peek()和c++中的top()只返回头，不移除，pop要移除
    public void push(int node) {
        if(mData.empty()){
            mMin.push(node);
        }
        
        if(node<mMin.peek()){
            mMin.push(node);
        }else{
            
            mMin.push(mMin.peek());
        }
        mData.push(node);
    }
    
    public void pop() {
        if(mData.size()>0&&mMin.size()>0){
            mData.pop();
               mMin.pop();
        }
     }
        
    
    public int top() {
        
        return (int)mData.peek();
    }
    
    public int min() {
        if(mMin.empty()){
            return 0;
        }
        return (int)mMin.peek();
    }