- Added folder for Challenge - 021.

1 files changed, 25 insertions, 0 deletions

diff --git a/challenge-021/duncan-c-white/README b/challenge-021/duncan-c-white/README
new file mode 100644
index 0000000000..bf5b030e87
--- /dev/null
+++ b/challenge-021/duncan-c-white/README
@@ -0,0 +1,25 @@
+Challenge 1: "Write a script to accept a string from command line and
+split it on change of character. For example, if the string is "ABBCDEEF",
+then it should split like 'A', 'BB', 'C', 'D', 'EE', 'F'."
+
+My notes: Clearly defined, sounds like a job for regexes.
+
+
+Challenge 2: "Write a script to print the smallest pair of Amicable Numbers."
+
+Amicable numbers are two different numbers so related that the sum of the
+proper divisors of each is equal to the other number. (A proper divisor
+of a number is a positive factor of that number other than the number
+itself. For example, the proper divisors of 6 are 1, 2, and 3.)
+
+The smallest pair of amicable numbers is (220, 284). They are amicable
+because the proper divisors of 220 are 1, 2, 4, 5, 10, 11, 20, 22, 44,
+55 and 110, of which the sum is 284; and the proper divisors of 284 are 1,
+2, 4, 71 and 142, of which the sum is 220.
+
+The first ten amicable pairs are: (220, 284), (1184, 1210), (2620,
+2924), (5020, 5564), (6232, 6368), (10744, 10856), (12285, 14595),
+(17296, 18416), (63020, 76084), and (66928, 66992)
+
+My notes: Another clearly described problem.  Obvious method involves
+a bit of caching.