hdu 2133 What day is it(蔡勒公式)

http://acm.hdu.edu.cn/showproblem.php?pid=2133

　　蔡勒公式求某一天是周几。

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 1 /*** 蔡勒公式，求某一天是周几（hdu 2133）***/
 2 #include <cstdio>
 3 
 4 const char *ans[7] = {"Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"};
 5 
 6 int isLeap(int y) { // 判断是否闰年
 7     return !(y % 4) && (y % 100) || !(y % 400);
 8 }
 9 
10 int mod(int a, int b) { // 保证取模后是正数
11     return (a % b + b) % b;
12 }
13 int main() {
14     int y, m, d, c, w;
15 
16     while (~scanf("%d%d%d", &y, &m, &d)) {
17         if (d <= 0 || m <= 0 || d >= 10000 || m > 12 || d > 31) {
18             printf("illegal\n");
19             continue;
20         }
21         if (!isLeap(y) && m == 2 && d > 28) {
22             printf("illegal\n");
23             continue;
24         }
25         if (isLeap(y) && m == 2 && d > 29) {
26             printf("illegal\n");
27             continue;
28         }
29         if ((m == 4 || m == 6 || m == 9 || m == 11) && d > 30) {
30             printf("illegal\n");
31             continue;
32         }
33         if (m == 1 || m == 2) m += 12, y--;
34         /*** 蔡勒公式 ***/
35         c = y / 100;
36         y %= 100;
37         w = (c >> 2) - (c << 1) + y + (y >> 2) + 13 * (m + 1) / 5 + d - 1;
38         printf("%s\n", ans[mod(w, 7)]);
39         /****************/
40     }
41     return 0;
42 }

——written by Lyon

posted @ 2012-11-06 03:45 LyonLys 阅读(196) 评论(0) 收藏举报

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