Enumerate the exercises

05_greatest_common_divisor.lua

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+-- The greatest common divisor (GCD) of two numbers is, as the name
+-- suggests, the largest number which evenly divides both.  Implement
+-- the function below to calculate this.  It's recommended that you
+-- use Euclid's algorithm but feel free to use another approach if you
+-- want.
+--
+-- Solution --------------------------------------------------------------------
+function greatest_common_divisor(x, y)
+	-- Your implementation here
+end
+
+-- Tests -----------------------------------------------------------------------
+
+local luaunit = require("luaunit.luaunit")
+
+function test_greatest_common_divisor_of_1386_and_3213_is_63()
+	luaunit.assertEquals(greatest_common_divisor(1386, 3213), 63)
+end
+
+function test_greatest_common_divisor_of_1470_and_3234_is_294()
+	luaunit.assertEquals(greatest_common_divisor(1470, 3234), 294)
+end
+
+function test_greatest_common_divisor_of_931_and_399_is_133()
+	luaunit.assertEquals(greatest_common_divisor(931, 399), 133)
+end
+
+os.exit(luaunit.LuaUnit.run())