luqinghui

public class Date_My {
    private final int value;
    public Date_My(int year, int month, int day){
        value = year*512 + month*32 + day;
        // value = y * 2^9 + m * 2^5+ d;
    }
    public int month(){
        return (value / 32) % 16;
        // 除以32后，剩下 y*2^4 + m（d消掉了，2^4 = 2^9 / 2^5），接着再用16(即2^4)取余,得month
    }