From 20a89cc87090a2dab9c7ea1e50cfb9e24943103f Mon Sep 17 00:00:00 2001
From: Dan Ballard <dan@mindstab.net>
Date: Fri, 21 Oct 2011 12:49:42 -0700
Subject: [PATCH] added prolog e3

---
 e3/e3.pl | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 e3/e3.pl

diff --git a/e3/e3.pl b/e3/e3.pl
new file mode 100644
index 0000000..768d8c0
--- /dev/null
+++ b/e3/e3.pl
@@ -0,0 +1,13 @@
+append([],[],[]).
+append([],[H|T], [H|Acc]) :- append([], T, Acc).
+append([H|T], L, [H|Acc]) :- append(T, L, Acc).
+
+factor(N, Divisor, [N]) :- N is 1; Divisor >= N - 1.
+factor(N, Divisor, Res) :- 0 is N rem Divisor, N1 is N/Divisor, factor(N1, 2, N1F), factor(Divisor, 2, DF), append(N1F, DF, Res).
+factor(N, Divisor, Res) :- N rem Divisor > 0, D2 is Divisor + 1, factor(N, D2, Res).
+
+max([], TMax, TMax).
+max([H|T], TMax, M) :- H > TMax, max(T, H, M).
+max([H|T], TMax, M) :- max(T, TMax, M).
+
+e3(Highest) :- factor(600851475143, 2, Factors), max(Factors, 0, Highest).