From 1d2e635f05d74807cddbbf90f43f982c5f7784a7 Mon Sep 17 00:00:00 2001
From: Evan Hemsley <evan.hemsley@gmail.com>
Date: Wed, 19 Oct 2016 14:34:59 -0700
Subject: [PATCH] solution to problem 003 in lisp

---
 lisp/euler.lisp    | 12 +++++++++++-
 lisp/euler003.lisp | 15 +++++++++++++++
 2 files changed, 26 insertions(+), 1 deletion(-)
 create mode 100644 lisp/euler003.lisp

diff --git a/lisp/euler.lisp b/lisp/euler.lisp
index 9f9679f..6d582b6 100644
--- a/lisp/euler.lisp
+++ b/lisp/euler.lisp
@@ -1,3 +1,13 @@
-(defun range (min max) (loop for n from min below max by 1 collect n))
+(defun range (min max) (loop for n from min below (+ max 1) by 1 collect n))
 (defun sum (list) (apply '+ list))
 (defun select (expr list) (remove-if-not expr list))
+(defun filter (expr list) (remove-if expr list))
+
+(defun partial (func &rest args1)
+  (lambda (&rest args2)
+    (apply func (append args1 args2)))
+)
+
+(defun prime (n)
+  (eq (length (member T (mapcar (lambda (a) (eq (mod n a) 0)) (range 2 (sqrt n))))) 0)
+)
diff --git a/lisp/euler003.lisp b/lisp/euler003.lisp
new file mode 100644
index 0000000..7292da8
--- /dev/null
+++ b/lisp/euler003.lisp
@@ -0,0 +1,15 @@
+(load "euler.lisp")
+
+(defun eratosthenes-helper (expr list-one list-two)
+  (if (> (length list-one) 0) (eratosthenes-helper expr (filter (partial expr (first list-one)) (rest list-one)) (filter (partial expr (first list-one)) list-two)) list-two)
+)
+
+(defun eratosthenes (n)
+  (eratosthenes-helper (lambda (x a) (and (eq (mod a x) 0) (/= a x))) (range 2 (sqrt n)) (range 2 n))
+)
+
+(defun prime-factors (n)
+  (select (lambda (a) (eq (mod n a) 0)) (eratosthenes (sqrt n)))
+)
+
+(defun solution () (first (reverse (prime-factors 600851475143))))