public int random05(){
        return (int) (Math.random()*5)+1;
    }

    //1.先等概率返回0,1
    public int random01(){
        if (random05()==1||random05()==2){
            return 0;
        }else if (random05()==4||random05()==5){
            return 1;
        }else {
            return random01();
        }
    }

    //2.等概率返回1-7
    public int random06(){
        int res=(random01()<<2)+(random01()<<1)+random01();
        if (res==7){
            return random06();
        }
        else {
            return res+1;
        }
    }