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erlang/leap/README.md

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+# Leap
+
+Write a program that will take a year and report if it is a leap year.
+
+The tricky thing here is that a leap year occurs:
+
+```plain
+on every year that is evenly divisible by 4
+  except every year that is evenly divisible by 100
+    unless the year is also evenly divisible by 400
+```
+
+For example, 1997 is not a leap year, but 1996 is.  1900 is not a leap
+year, but 2000 is.
+
+If your language provides a method in the standard library that does
+this look-up, pretend it doesn't exist and implement it yourself.
+
+## Notes
+
+For a delightful, four minute explanation of the whole leap year
+phenomenon, go watch [this youtube video][video].
+
+[video]: http://www.youtube.com/watch?v=xX96xng7sAE
+
+
+## Source
+
+JavaRanch Cattle Drive, exercise 3 [view source](http://www.javaranch.com/leap.jsp)

erlang/leap/leap_tests.erl

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+% To run tests:
+% erl -make
+% erl -noshell -eval "eunit:test(leap, [verbose])" -s init stop
+%
+
+-module(leap_tests).
+
+-include_lib("eunit/include/eunit.hrl").
+
+leap_year_test() ->
+  ?assert(leap:leap_year(1996)).
+
+non_leap_year_test() ->
+  ?assertNot(leap:leap_year(1997)).
+
+century_test() ->
+  ?assertNot(leap:leap_year(1900)).
+
+fourth_century_test() ->
+  ?assert(leap:leap_year(2400)).