#include<stdio.h>
int main(){
int x,y,ans=0;
int yue[12]={31,28,31,30,31,30,31,31,30,31,30,31};
scanf("%d %d",&x,&y);
if(x % 4 == 0&& x % 100 != 0 || x % 400 == 0)
yue[1]+=1;
ans+=yue[y-1];
printf("%d",ans);
return 0;
}``

```

```

#include <stdio.h> int main() { int x,y; int flag=0; scanf("%d %d",&x,&y); int a[2][13]={{31,28,31,30,31,30,31,31,30,31,30,31},{31,29,31,30,31,30,31,31,30,31,30,31}}; if((x%40&&x%100!=0)||x%4000) flag=1; printf("%d",a[flag][y-1]); return 0; }

// 处理每个月的天数 int days_in_month;

switch (month) { case 1: case 3: case 5: case 7: case 8: case 10: case 12: days_in_month = 31; break; case 4: case 6: case 9: case 11: days_in_month = 30; break; case 2: // 判断是否是闰年 if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) { days_in_month = 29; } else { days_in_month = 28; } break; default: days_in_month = 0; // 无效的月份 break; }

printf("%d\n", days_in_month); return 0;

#include <stdio.h>
int main()
{
    int a,b,c;
    scanf("%d%d",&a,&b);
    if(b==1||b==3||b==5||b==7||b==8||b==10||b==12)c=31;
    else if(b==4||b==6||b==9||b==11);
    else if((a%4==0&&(a%400==0||a%100!=0))&&b==2)c=29;
    else c=28;
    printf("%d",c);
    return 0;
}
//

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

#include<stdio.h> int main(){ int x,y;1<=y&&y<=12; scanf("%d %d",&x,&y); switch(y){ case 1: case 3: case 5: case 7: case 8: case 10: case 12: printf("31");break; case 4: case 6: case 9: case 11: printf("30");break; case 2: if(x%40&&x%100!=0||x%4000) {printf("29"); }else printf("28");break; } return 0; }

#include<stdio.h>
int main(){
	int x,y ;
	scanf("%d%d",&x,&y);
		if(y==1||y==3||y==5||y==7||y==8||y==10||y==12){
	printf("31");
		}
		else
		if(y==6||y==4||y==9||y==11)
		{printf("30");
		}
		else
		if(y==2)
		{
			if((x%400==0)||(x%4==0&&x%100!=0)){
			printf("29");	
			}
			else{
				printf("28");
			}}return 0;
		}

#include<stdio.h>
int main(){
	int x,y ;
	scanf("%d%d",&x,&y);
		if(y==1||y==3||y==5||y==7||y==8||y==10||y==12){
	printf("31");
		}
		else
		if(y==6||y==4||y==9||y==11)
		{printf("30");
		}
		else
		if(y==2)
		{
			if((x%400==0)||(x%4==0&&x%100!=0)){
			printf("29");	
			}
			else{
				printf("28");
			}}return 0;
		}