【HDOJ】2133 What day is it

需要注意数据有效性。

#include <stdio.h>

#define isLeapYear(y) (y%4==0&&y%100!=0)||(y%400==0)

int nums[2][13] = {{0,31,28,31,30,31,30,31,31,30,31,30,31}, {0,31,29,31,30,31,30,31,31,30,31,30,31}};
char buf[7][20] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};

int main() {
    int i, j, year, month, day, total;

    while (scanf("%d %d %d", &year, &month, &day) != EOF) {
        total = day;
        j = isLeapYear(year);
        if (month==0 || day==0) {
            printf("illegal
");
            continue;
        }
        for (i=1; i<month; ++i)
            total += nums[j][i];
        if (month == 2) {
            if (!j && day>28) {
                printf("illegal
");
                continue;
            }
            if (j && day>29) {
                printf("illegal
");
                continue;
            }
        }
        if ((month==4||month==6||month==9||month==11) && day>30) {
            printf("illegal
");
            continue;
        }
        for (i=1; i<year; ++i) {
            if (isLeapYear(i))
                total += 366;
            else
                total += 365;
        }
        i = total % 7;
        printf("%s
", buf[i]);
    }

    return 0;
}