输入某年某月某日，判断这一天是这一年中的第几天（注意闰年）


运行结果示例： 



public static void main(String[] args){
    int feb=28;
    Scanner sc=new Scanner(System.in);
    System.out.println("请输入年份");
    int year=sc.nextInt();
    System.out.println("请输入月");
    int month=sc.nextInt();
    System.out.println("请输入日");
    int day=sc.nextInt();
    if(year%4==0 && year%100!=0 || year%400==0){
      feb=29;
    }
    int sum = 0;
    switch(month){
    case 1  : sum=day;
    break;
    case 2  : sum=31+day;
    break;
    case 3  : sum=31+feb+day;
    break;
    case 4  : sum=31+feb+31+day;
    break;
    case 5  : sum=31+feb+31+30+day;
    break;
    case 6  : sum=31+feb+31+30+31+day;
    break;
    case 7  : sum=31+feb+31+30+31+30+day;
    break;
    case 8  : sum=31+feb+31+30+31+30+31+day;
    break;
    case 9  : sum=31+feb+31+30+31+30+31+31+day;
    break;
    case 10 : sum=31+feb+31+30+31+30+31+31+30+day;
    break;
    case 11 : sum=31+feb+31+30+31+30+31+31+30+31+day;
    break;
    case 12 : sum=31+feb+31+30+31+30+31+31+30+31+30+day;
    break;
    }
    System.out.println(year+"年 "+month+"月 " + day + "号是"+year+"年的第"+sum+"天");
  }