project-euler: Rewrap, update links, add copyrights, tests

[factor.git] / extra / project-euler / 023 / 023.factor

diff --git a/extra/project-euler/023/023.factor b/extra/project-euler/023/023.factor
index 0b6fa66fcf1c40250ad2652d49bef99986e0dc49..86f0e3fa70e4c5d994117cfa22488a005dcc08bc 100644 (file)
--- a/extra/project-euler/023/023.factor
+++ b/extra/project-euler/023/023.factor
@@ -1,38 +1,41 @@
 ! Copyright (c) 2008 Aaron Schaefer.
 ! See https://factorcode.org/license.txt for BSD license.
-USING: kernel math ranges project-euler.common
-sequences sets ;
+USING: kernel math ranges project-euler.common sequences sets ;
 IN: project-euler.023
 
-! https://projecteuler.net/index.php?section=problems&id=23
+! https://projecteuler.net/problem=23
 
 ! DESCRIPTION
 ! -----------
 
-! A perfect number is a number for which the sum of its proper divisors is
-! exactly equal to the number. For example, the sum of the proper divisors of
-! 28 would be 1 + 2 + 4 + 7 + 14 = 28, which means that 28 is a perfect number.
+! A perfect number is a number for which the sum of its proper
+! divisors is exactly equal to the number. For example, the sum
+! of the proper divisors of 28 would be 1 + 2 + 4 + 7 + 14 = 28,
+! which means that 28 is a perfect number.
 
-! A number whose proper divisors are less than the number is called deficient
-! and a number whose proper divisors exceed the number is called abundant.
+! A number whose proper divisors are less than the number is
+! called deficient and a number whose proper divisors exceed the
+! number is called abundant.
 
-! As 12 is the smallest abundant number, 1 + 2 + 3 + 4 + 6 = 16, the smallest
-! number that can be written as the sum of two abundant numbers is 24. By
-! mathematical analysis, it can be shown that all integers greater than 28123
-! can be written as the sum of two abundant numbers. However, this upper limit
-! cannot be reduced any further by analysis even though it is known that the
-! greatest number that cannot be expressed as the sum of two abundant numbers
-! is less than this limit.
+! As 12 is the smallest abundant number, 1 + 2 + 3 + 4 + 6 = 16,
+! the smallest number that can be written as the sum of two
+! abundant numbers is 24. By mathematical analysis, it can be
+! shown that all integers greater than 28123 can be written as
+! the sum of two abundant numbers. However, this upper limit
+! cannot be reduced any further by analysis even though it is
+! known that the greatest number that cannot be expressed as the
+! sum of two abundant numbers is less than this limit.
 
-! Find the sum of all the positive integers which cannot be written as the sum
-! of two abundant numbers.
+! Find the sum of all the positive integers which cannot be
+! written as the sum of two abundant numbers.
 
 
 ! SOLUTION
 ! --------
 
-! The upper limit can be dropped to 20161 which reduces our search space
-! and every even number > 46 can be expressed as a sum of two abundants
+! The upper limit can be dropped to 20161 which reduces our
+! search space and every even number > 46 can be expressed as a
+! sum of two abundants
 
 <PRIVATE