计算星期五13日的未来发生 [英] Calculating future occurences of Friday the 13th

问题描述

我想要能够从一年开始，并计算出13日的周五。蛮力解决方案很简单明了。我有点更好一点，但我毫不怀疑，其他人可以提出一个优雅的算法。

也许有点棘手，我会感兴趣给予该计划一个月，并找到明年的那个月有一个星期五13日。

随意使用伪代码，但我希望人们会对您最喜欢的语言的工作代码示例进行投票。

-Adam

解决方案

从星期天开始的任何一个月都有第十三个星期五。只有14个组合可能知道今年第一天（有或没有闰年，晒太阳）。你应该只是计算一次，并得到它。

生成的表格元素（从2009年的2010年）：

  [Thursday，false] => Feb，March，Nov 
 [Friday，false] => 8月
  

填写表，你有一个通用月份Jan（31），Feb（28）..然后用一周的每一天的种子进行迭代，注意到从星期天开始的几个月，并且还有一个闰年和没有。很简单，一旦完成，您可以与我们分享：）

I'd like to be able to start with a year, and calculate occurrences of Friday the 13th. A brute force solution is easy and obvious. I have something slightly better, but I have no doubt that someone else can come up with an elegant algorithm for this.

Perhaps a little trickier, I'd be interested in giving the program a month, and have it find the next year in which that month has a Friday the 13th.

Feel free to use pseudo code, but I expect people will vote more for working code samples in you favorite language.

-Adam

解决方案

Any month that starts with a Sunday has a Friday on the thirteenth. There are only 14 combinations possible knowing what day the first of the year is on (with or without leap year, and sun-sat). You should just calculate it once and get it over with. You'd only check 14*12 possible months to start out with, well with in reason.

resultant table element (from 2009, 2010):

[Thursday,false] => Feb, March, Nov
[Friday,false] => Aug

to fill the table you have a generic month Jan(31),Feb(28).. and then iterate with a seed of each day of the week, noting months that start with sunday, and also with a leap year and without. Pretty straight forward, and once done, you can share it with us :)

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