题解 | #打印日期#

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int[][] a = {{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}, 
        {0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};
        //当年数不能被100整除时，若其能被4整除或400整除时，则为闰年
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int year = in.nextInt();
            int _day = in.nextInt();

            PrintDate(a,_day,year);
            
        }
    }
    //判断输入的年份是否是闰年
    public static boolean IsRunYear(int year) {
        if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
            return true;
        }
        return false;
    }
    //根据年份，第几天等信息打印日期
    public static void PrintDate(int[][] a, int _day, int year) {
        int j = IsRunYear(year) ? 1 : 0;
        int month = 0;
        for (int i = 0 ; i < a[0].length ; ++i) {
            if (_day > a[j][i]) {
                _day = _day - a[j][i];
            } else {
                month = i;
                break;
            }
        }
        System.out.println(year + "-" + (month < 10 ? "0" + month : month) + "-" +(_day < 10 ? "0" + _day : _day));
    }
}