题目：输入某年某月某日，判断这一天是这一年的第几天？ 1.程序分析：以3月5日为例，应该先把前两个月的加起来， 然后再加上5天即本月的第几天，特殊情况， 闰年且输入月份大于3时需考虑多加一天

public class min {
public static void main(String[] args) {
int year, month, day, sum = 0;
Scanner scanner = new Scanner(System.in);
System.out.println("输入年：");
year = scanner.nextInt();
System.out.println("输入月：");
month = scanner.nextInt();
System.out.println("输入日：");
day = scanner.nextInt();
switch (month) {
case 1:
sum = 0;
break;
case 2:
sum = 31;
break;
case 3:
sum = 59;
break;
case 4:
sum = 90;
break;
case 5:
sum = 120;
break;
case 6:
sum = 151;
break;
case 7:
sum = 181;
break;
case 8:
sum = 212;
break;
case 9:
sum = 243;
break;
case 10:
sum = 273;
break;
case 11:
sum = 304;
break;
case 12:
sum = 334;
break;
default:
System.out.println("输入错误");
return;
}


sum = sum + day;
boolean leap;
if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {
leap = true;
} else {
leap = false;
}
if (leap && month > 2) {
sum++;
}


System.out.println("是这一年的第 " + sum + "天");
}
}