算法提高 日期计算

import java.io.BufferedInputStream;
import java.util.Scanner;

public class Main {

    public static boolean IsLeap(int year){
        if (year % 4 == 0 && year % 100 != 0){
            return true;
        }
        if (year % 400 == 0)
            return true;
        return false;
    }

    public static long Week(int year ,int month, int day){
        long sum = 0;
        for( int i = 1 ; i < year ; i++){
            if (IsLeap(i)){
                sum += 366;
            }else{
                sum += 365;
            }
        } 
        for( int i = 1 ; i < month ; i++){  
            if(i==1||i==3||i==5||i==7||i==8||i==10||i==12)  
                 sum+=31;  
            if(i==4||i==6||i==9||i==11)  
                 sum+=30;  
            if(i==2&&IsLeap(year))  
                 sum+=29;  
            if(i==2&&!IsLeap(year))  
                 sum+=28;
        }  
        sum += day;
        sum %= 7;
        return sum;  
    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in= new Scanner(new BufferedInputStream(System.in));
        String str = in.nextLine();
        String[] split = str.split(" ");
        int year = Integer.parseInt(split[0]);
        int month = Integer.parseInt(split[1]);
        int day = Integer.parseInt(split[2]);
        System.out.println(Week(year, month, day));
        in.close();
    }
}