102 lines
2.8 KiB
C++
102 lines
2.8 KiB
C++
#include <stdio.h>
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int calculate(int year, int month, int day);
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int main()
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{
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const char *weekdays[] =
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{
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"Sunday", "Monday", "Tuesday", "Wednesday",
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"Thursday", "Friday", "Saturday"
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};
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const char *monthname[] =
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{
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"January", "February", "March", "April",
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"May", "June", "July", "August",
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"September", "October", "November", "December"
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};
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int year, month, day, week;
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while (scanf("%d%d%d", &month, &day, &year) != EOF)
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{
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if (year == 0 && month == 0 && day == 0)
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break;
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week = calculate(year, month, day);
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if (week == -1)
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printf("%d/%d/%d is an invalid date.\n", month, day, year);
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else
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printf("%s %d, %d is a %s\n", monthname[month - 1], day, year, weekdays[week]);
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}
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return 0;
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}
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int calculate(int year, int month, int day)
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{
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int count, leap, century;
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static const int daycount[] =
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{ 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 };
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if (year <= 0 || month > 12 || month < 1 || day < 1 || day > 31)
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return -1;
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if ((month == 4 || month == 6 || month == 9 || month == 11) && day > 30)
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return -1;
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if (year <= 1752)
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{
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if (year == 1752 && month == 9 && day > 2 && day < 14)
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return -1;
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if (year % 4 == 0)
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{
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leap = 1;
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if (month == 2)
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{
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if (day > 29)
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return -1;
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}
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}
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else
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{
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leap = 0;
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if (month == 2)
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{
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if (day > 28)
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return -1;
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}
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}
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count = (year - 1) * 365 + (year - 1) / 4;
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count += daycount[month - 1] + day;
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if (leap && month > 2)
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count += 1;
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if (year == 1752)
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{
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if (month > 9 || (month == 9 && day >= 14))
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count -= 11;
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}
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return ((count + 5) % 7);
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}
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else
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{
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if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0)
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{
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leap = 1;
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if (month == 2)
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{
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if (day > 29)
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return -1;
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}
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}
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else
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{
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leap = 0;
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if (month == 2)
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{
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if (day > 28)
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return -1;
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}
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}
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century = (year - 1) / 100 - 17;
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count = (year - 1) * 365 + (year - 1) / 4;
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count += (daycount[month - 1] + day);
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count -= (11 + century);
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count += (century + 1) / 4;
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if (leap && month > 2)
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count += 1;
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return ((count + 5) % 7);
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}
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return -1;
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}
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