算法训练 黑色星期五

import java.util.Scanner;
public class Main {
    static int getweekoffirstday(int y){
        int i=1998,week=3;
        int days=0;
        for(i=1998;i<y;i++){
            if(i%400==0||(i%4==0&&i%100!=0))
                days+=366;
            else
                days+=365;
        }
        return (days+week)%7;
    }
    static void print(int y){
        int day[][]={{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}};
    int week=getweekoffirstday(y),flag=y%400==0||(y%4==0&&y%100!=0)?1:0;
    int times=0,i,days=0;
    for(i=0;i<12;i++){
        if((days+12+week)%7==4)
            times++;
        days+=day[flag][i];
    }
    System.out.println(times);
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc=new Scanner(System.in);
        int y=sc.nextInt();
        print(y);

    }

}