什么是回文日期?

什么是回文日期?

You've likely heard that palindrome sentence that is spelled the same way forwards and backwards. But palindrome dates seem to spark a lot of curiosity and discussion.

你可能聽說過回文句子，前后拼寫相同。但是回文日期似乎引發(fā)了很多好奇和討論。

Palindrome dates only occur in the early centuries of a millennium. (Photo: Vintage Vectors Studio/Shutterstock)

Palindrome dates, by their very nature, only occur in the early centuries of a millennium. There will be 36 of them during this millennium — the last one will be on Sept. 22, 2290. The next one after that won't be until Oct. 3, 3001.

回文日期，就其本質(zhì)而言，只發(fā)生在一個(gè)世紀(jì)的早期。在這個(gè)千禧年里，將會有36個(gè)，最后一個(gè)是在2290年9月22日。在那之后的下一次將會在3001年10月3日。

In 2019, for example, every day for 10 consecutive days starting Sept. 10 is a palindrome in the m-dd-yy format, which is common in the United States:

例如，在2019年，從9月10日開始連續(xù)10天的每一天都是m-dd-yy格式的回文，這在美國很常見:

9-10-19

9-11-19

9-12-19

9-13-19

9-14-19

9-15-19

9-16-19

9-17-19

9-18-19

9-19-19

Palindromic dates can be rare, depending on how a date is formatted.

回文日期可能很少，這取決于日期的格式。

Aziz S. Inan, an electrical engineering professor at the University of Portland, has calculated that when dates are written in the mm-dd-yyyy format, palindrome days typically occur only in the first few centuries of each millennium. The last palindromic date in the second millennium (1001 to 2000) in this format was Aug. 31, 1380 or 08-31-1380, according to timeanddate.com. The first one in the current millennium (Jan. 1, 2001 to Dec. 31, 3000) was Oct. 2, 2001 (10-02-2001) and the last one will be Sept. 22, 2290 (09-22-2290).

阿齊茲·s·伊南(Aziz S. Inan)是波特蘭大學(xué)(University of Portland)的電氣工程教授，他計(jì)算出，當(dāng)日期以mm-dd-yyyy格式書寫時(shí)，回文日通常只出現(xiàn)在每個(gè)千年的頭幾個(gè)世紀(jì)。據(jù)timeanddate.com稱，第二個(gè)千禧年(1001年至2000年)最后一個(gè)回文日期是1380年8月31日或08-31-1380年。當(dāng)前千禧年(2001年1月1日至3000年12月31日)的第一次是2001年10月2日(10-02-2001)，最后一次是2290年9月22日(09-22-2290)。

For countries that use the dd-mm-yyyy format, there are 29 palindrome days in the current century. The first was 10 February 2001 (10-02-2001). The last will be a leap day: 29 February 2092 (29-02-2092), which will also be the last palindrome day of the 21st century.

對于使用dd-mm-yyyy格式的國家，本世紀(jì)有29個(gè)回文日。第一次是2001年2月10日(10-02-2001)。最后一個(gè)將是閏日:2092年2月29日(29-02-2092)，這也是21世紀(jì)最后一個(gè)回文日。

Palindrome weeks

回文周

Although it might seem like strings of palindrome dates — or palindrome weeks — might be rare, Inan says that's hardly the case.

雖然這看起來像是一連串的回文日期——或者回文周——可能很少見，但伊南說情況并非如此。

Since 2011, every year has had 10 consecutive palindrome days. In 2011, they started on Jan. 10 (1-10-11 through 1-19-11), for example, and in 2012, another string started on Feb. 10 (2-10-12 through 2-19-12). In 2017, it happened in July, while in 2018, it happened in August.

自2011年以來，每年都有連續(xù)10個(gè)回文日。例如，2011年1月10日開始(1-10-11到1-19-11)，2012年2月10日開始(2-10-12到2-19-12)。2017年發(fā)生在7月，而2018年發(fā)生在8月。

In the m-dd-yy format, every century has nine years with 10 consecutive palindrome days. Timeanddate.com points out that they're always in the second decade of the century. Every year between 2011-2019, 2111-2119, and 2211-2219 will have 10 palindrome days in a row.

在m-dd-yy格式中，每個(gè)世紀(jì)有9年，連續(xù)10個(gè)回文日。Timeanddate.com指出，它們總是在本世紀(jì)的第二個(gè)十年。2011-2019年，2111-2119年和2211-2219年將會有連續(xù)10個(gè)回文日。

But palindrome dates aren't the only way that calendar number geeks — I mean enthusiasts — get their thrills.

但是回文日期并不是日歷數(shù)字極客(我是說發(fā)燒友)獲得興奮的唯一方式。

Among other patterns, there are repeating dates (1/11/11 = 11111), repeating sequences (10/31/03 = 103 103), and sequential dates (8/9/10 = 8,9,10; and if you start with the time of 12:34:56.7, you get 1, 2, 3, 4, 5, 6, 7, 8, 9, 10).

在其他模式中，有重復(fù)日期(1/11/11 = 11111)、重復(fù)序列(10/31/03 = 103 103)和順序日期(8/9/10 = 8,9,10;如果從12:34:56.7開始，得到12 34 56 7 8 9 10)。