#include <stdio.h>

int main() {
    int choice;
    int j,k,l,m,n;
    printf("菜单选项：\n");
    printf("1.查询对应年份的日历\n");
    printf("2.查询对应日期的星期\n");
    printf("3.查询对应年份是否为闰年\n");
    printf("4.退出\n");
    printf("请输入你的选择(1-4)：");
    scanf("%d", &choice);
    start:
    switch (choice) {
        case 1:
		
            printf("请输入需要查询的年份\n");
            
    int year;
	scanf("%d", &year);
    int month,day;
    int i,k;
    

    // 单列输出日历
    printf("单列日历输出如下：\n");
      for (month = 1; month <= 12; month++) {
        // 每个月的天数数组，先按非闰年设置，后续根据是否闰年调整2月天数
        int daysInMonth[] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
        if ((year % 4 == 0 && year % 100!= 0) || year % 400 == 0) {
            daysInMonth[1] = 29;
        }

        // 计算该月1号是星期几，蔡氏公式简化版思路
        int y = year % 100;
        int c = year / 100;
        if (month < 3) {
            y -= 1;
            c -= 1;
        }
        int firstDay = (1 + (13 * (month + 1) / 5) + y + (y / 4) + (c / 4) - 2 * c) % 7;
        firstDay = firstDay < 0? firstDay + 7 : firstDay;

        // 输出月份标题
        printf("     %d年%d月\n", year, month);
        printf("日 一 二 三 四 五 六\n");

        // 输出该月1号前的空格
        for (i = 0; i < firstDay; i++) {
            printf("   ");
        }

        // 输出该月每天的日期
        int numDays = daysInMonth[month - 1];
        for (day = 1; day <= numDays; day++) {
            printf("%2d ", day);
            if ((firstDay + day) % 7 == 0) {
                printf("\n");
            }
        }

        // 如果该月最后一行不满7个，补充换行
        if ((firstDay + numDays) % 7!= 0) {
            printf("\n");
        }

        printf("\n");
    }

   

    
		break;
        
        case 2:
        	
            printf("请输入需要查询的日期\n");
            {
			
           printf("请输入该查询的年份：\n");
            scanf("%d",&year);
            printf("请输入该查询的月份：\n");
            scanf("%d",&month);
            printf("请输入该查询的日期: \n");
            scanf("%d",&day);
            if(month<3)
            {
            	year--;
            	month+=12;
			}
			k=year%100;j=year/100;l=day;m=month;
			n=(l+(26*(m+1)/10)+k+(k/4)+(j/4)+5*j)%7;
			switch(n)
			{
				case 0:
					printf("星期六");
					break;
				case 1:
					printf("星期日");
					break;
				case 2:
					printf("星期一");
					break;
				case 3:
					printf("星期二");
					break;
				case 4:
					printf("星期三");
					break;
				case 5:
					printf("星期四");
					break;
				case 6:
					printf("星期五");
					break;
			}
            break;
        }
    
        case 3:
            printf("请输入需要查询的年份\n");
            {
			
    int year;
    printf("请输入一个年份：");
    scanf("%d", &year);
    if ((year % 4 == 0 && year % 100!= 0) || year % 400 == 0) {
        printf("%d年是闰年\n", year);
    } else {
        printf("%d年不是闰年\n", year);
    }
    
}
    break;
        case 4:
            printf("正在退出程序...\n");
            break;
        default:
            
            printf("无效的选择，请重新输入(1~4)\n");
            scanf("%d",&choice);
            if(choice<=4)
            {
            	goto start;
			}
    }


    return 0;
}