int sum=0; //统计总天数
    for(int i=1;i<=a2-1;i++) //因为某一月时，本月不算所以要减一
    {
      int day=0;
      switch(i)
      {
      case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:
      case 12:day=31;break; //都是31天的为一类
      case 4:
      case 6:
      case 9:
      case 11:day=30;break; //都是30天的为一类
      case 2:{
                //二月份比较特殊，需要判断是否为闰年
        if((a1%400==0) || (a1%4==0 && a1%100!=0))
        {
          day=29;break;
        }else {
          day=28;break;
        }
      }
      }
      sum+=day; //每一次循环，加一次
    }
    sum+=a3; //本月的天数直接加上

import java.util.*;
public class exercise11 {
  public static void main(String[] args) {
    Scanner s = new Scanner(System.in);
    System.out.print("请输入年：");
    int a1 = s.nextInt();
    System.out.print("请输入月：");
    int a2 = s.nextInt();
    System.out.print("请输入日：");
    int a3 = s.nextInt();
    int sum=0;
    for(int i=1;i<=a2-1;i++)
    {
      int day=0;
      switch(i)
      {
      case 1:
      case 3:
      case 5:
      case 7:
      case 8:
      case 10:
      case 12:day=31;break;
      case 4:
      case 6:
      case 9:
      case 11:day=30;break;
      case 2:{
        if((a1%400==0) || (a1%4==0 && a1%100!=0))
        {
          day=29;break;
        }else {
          day=28;break;
        }
      }
      }
      sum+=day;
    }
    sum+=a3;
    System.out.println("这是这一年中第"+sum+"天");
  }
}