大一新生
#include <stdio.h> int main() { int year,month; while(scanf("%4d %2d",&year,&month)!=EOF) { if (year%100!=0&&year%4==0)//闰年 { switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12:printf("31\n"); break; case 2:printf("29\n"); break; case 4: case 6: case 9: case 11:printf("30\n"); } } else if (year%400==0)//闰年 { switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12:printf("31\n"); break; case 2:printf("29\n"); break; case 4: case 6: case 9: case 11:printf("30\n"); } } else //非闰年 { switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12:printf("31\n"); break; case 2:printf("28\n"); break; case 4: case 6: case 9: case 11:printf("30\n"); } } } return 0; }