From 1d6c80344bff3b0761a2eacf2943b3b5529418a3 Mon Sep 17 00:00:00 2001
From: Jack Kinsey <j.jameskinsey@gmail.com>
Date: Tue, 3 Dec 2019 23:24:23 -0500
Subject: [PATCH] Add correct day3pt2 solution

---
 src/adventofcode2019/day03.clj | 22 +++++++++++++---------
 1 file changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/adventofcode2019/day03.clj b/src/adventofcode2019/day03.clj
index 17564de..d21968f 100644
--- a/src/adventofcode2019/day03.clj
+++ b/src/adventofcode2019/day03.clj
@@ -19,32 +19,36 @@
 
 (defn ints-between [x y]
   (cond 
-    (> x y) (range y (inc x))
+    (> x y) (reverse (range y (inc x)))
     (< x y) (range x (inc y))
     :else [x]))
 
 (defn points-diff [pos-a pos-b]
   (let [[a-x a-y] pos-a
         [b-x b-y] pos-b]
-    (set (for [x (ints-between a-x b-x)
-               y (ints-between a-y b-y)]
-              [x y]))))
+    (rest (for [x (ints-between a-x b-x)
+                y (ints-between a-y b-y)]
+               [x y]))))
 
 (defn wire-spec->points [wire]
   (let [wire-ops (map spec->op wire)
         trace-reduction (fn [{:keys [pos points]} op]
                             (let [new-pos (op pos)
                                   new-points (points-diff pos new-pos)]
-                              {:pos new-pos :points (set/union points new-points)}))
-        trace (reduce trace-reduction {:pos [0 0], :points #{}} wire-ops)]
+                              {:pos new-pos :points (concat points new-points)}))
+        trace (reduce trace-reduction {:pos [0 0], :points []} wire-ops)]
     (:points trace)))
 
 (defn find-intersections [wires]
-  (let [wires-points (map wire-spec->points wires)]
-    (set/difference (apply set/intersection wires-points) #{[0 0]})))
+  (let [wires-points (map wire-spec->points wires)
+        intersections (apply set/intersection (map set wires-points))
+        find-steps (fn [i pos] (when (intersections pos) {pos (inc i)}))
+        step-counts (map #(map-indexed find-steps %) wires-points)]
+    (apply (partial merge-with +) (flatten step-counts))))
 
 (defn day03 []
   (let [wires (parse-input (input-file))
         manhattan-distance (fn [[x y]] (+ (Math/abs x) (Math/abs y)))
         intersections (find-intersections wires)] 
-    (println (apply min (map manhattan-distance intersections)))))
+    (println (apply min (map manhattan-distance (keys intersections))))
+    (println (apply min (vals intersections)))))
-- 
2.26.2