From cff06d70fdd9d802648d7f58fa65d887e30b9f2c Mon Sep 17 00:00:00 2001
From: Jack Kinsey <j.jameskinsey@gmail.com>
Date: Mon, 9 Dec 2019 19:50:47 -0500
Subject: [PATCH] Fix Intcode bug (uninitialized memory was nil)
---
src/adventofcode2019/intcode.clj | 17 +++++++++--------
1 file changed, 9 insertions(+), 8 deletions(-)
diff --git a/src/adventofcode2019/intcode.clj b/src/adventofcode2019/intcode.clj
index 252a613..dc542dd 100644
--- a/src/adventofcode2019/intcode.clj
+++ b/src/adventofcode2019/intcode.clj
@@ -9,10 +9,11 @@
op (vec (drop 3 str-code))
apply-flag (fn [flag arg]
(case flag
- \0 (fn ([S] (get-in S [:memory arg]))
+ ;; ORs avoid returning nil
+ \0 (fn ([S] (or (get-in S [:memory arg]) 0))
([_ _] arg))
\1 (constantly arg)
- \2 (fn ([S] (get-in S [:memory (+ arg (:relctr S))]))
+ \2 (fn ([S] (or (get-in S [:memory (+ arg (:relctr S))]) 0))
([S _] (+ arg (:relctr S))))))
with-flags (fn [f]
(fn [S & args]
@@ -21,20 +22,20 @@
(case op
[\0 \1] (fn [S a b c] ; ADD
(-> S
- (assoc-in [:memory (c S 0)] (+' (a S) (b S)))
+ (assoc-in [:memory (c S true)] (+' (a S) (b S)))
(update :ctr + 4)))
[\0 \2] (fn [S a b c] ; MULT
(-> S
- (assoc-in [:memory (c S 0)] (*' (a S) (b S)))
+ (assoc-in [:memory (c S true)] (*' (a S) (b S)))
(update :ctr + 4)))
[\0 \3] (fn [S a _ _] ; IN
(-> S
- (assoc-in [:memory (a S 0)] (first (:input S)))
+ (assoc-in [:memory (a S true)] (first (:input S)))
(update :input subvec 1)
(update :ctr + 2)))
[\0 \4] (fn [S a _ _] ; OUT
(-> S
- (update :output conj (get-in S [:memory (a S 0)]))
+ (update :output conj (or (get-in S [:memory (a S true)]) 0))
(update :ctr + 2)))
[\0 \5] (fn [S a b _] ; BNEQ
(update S :ctr (if (not= (a S) 0) (constantly (b S)) #(+ % 3))))
@@ -42,11 +43,11 @@
(update S :ctr (if (= (a S) 0) (constantly (b S)) #(+ % 3))))
[\0 \7] (fn [S a b c] ; SLT
(-> S
- (assoc-in [:memory (c S 0)] (if (< (a S) (b S)) 1 0))
+ (assoc-in [:memory (c S true)] (if (< (a S) (b S)) 1 0))
(update :ctr + 4)))
[\0 \8] (fn [S a b c] ; SEQ
(-> S
- (assoc-in [:memory (c S 0)] (if (= (a S) (b S)) 1 0))
+ (assoc-in [:memory (c S true)] (if (= (a S) (b S)) 1 0))
(update :ctr + 4)))
[\0 \9] (fn [S a _ _] ; SREL
(-> S
--
2.38.5