57 lines
1.5 KiB
Java
57 lines
1.5 KiB
Java
class Doom {
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public static void main(String[] args) {
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final Date[] dates = {
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new Date(1800,1,6),
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new Date(1875,3,29),
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new Date(1915,12,7),
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new Date(1970,12,23),
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new Date(2043,5,14),
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new Date(2077,2,12),
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new Date(2101,4,2)
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};
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for (Date d : dates)
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System.out.println(
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String.format("%s: %s", d.format(), d.weekday()));
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}
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}
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class Date {
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private int year, month, day;
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private static final int[] leapdoom = {4,1,7,4,2,6,4,1,5,3,7,5};
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private static final int[] normdoom = {3,7,7,4,2,6,4,1,5,3,7,5};
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public static final String[] weekdays = {
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"Sunday", "Monday", "Tuesday", "Wednesday",
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"Thursday", "Friday", "Saturday"
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};
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public Date(int year, int month, int day) {
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this.year = year;
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this.month = month;
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this.day = day;
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}
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public boolean isLeapYear() {
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return year%4 == 0 && (year%100 != 0 || year%400 == 0);
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}
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public String format() {
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return String.format("%02d/%02d/%04d", month, day, year);
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}
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public String weekday() {
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final int c = year/100;
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final int r = year%100;
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final int s = r/12;
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final int t = r%12;
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final int c_anchor = (5 * (c%4) + 2) % 7;
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final int doom = (s + t + t/4 + c_anchor) % 7;
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final int anchor =
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isLeapYear() ? leapdoom[month-1] : normdoom[month-1];
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return weekdays[(doom + day - anchor + 7) % 7];
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}
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}
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