Day01--栈--点击消除

public static void main(String[] args) {
        //Character是字符类型
        Stack<Character> stack = new Stack();
        Scanner sc = new Scanner(System.in);
        String str = sc.nextLine();
        for(int i = 0; i<str.length();i++){
            //如果是空栈，则直接入栈
            if(stack.empty()){
                stack.push(str.charAt(i));
                //如果相等，则出栈
            }else if(str.charAt(i) == stack.peek()){
                stack.pop();
            }else {
                //如果不空也不相等，直接入栈
                stack.push(str.charAt(i));
            }
        }
        //如果最后是空
        if (stack.empty())
            System.out.println(0);
        String s = "";
        while(!stack.empty()){
            s = s + stack.pop();
        }
        //因为栈顶元素在前面，得反过来
        for (int i = s.length()-1; i >= 0; i--) {
            System.out.print(s.charAt(i));
        }
    }