From 2dea655ee8f2c564b8401c47b05d51b59b3d698c Mon Sep 17 00:00:00 2001
From: Bruno Raoult <braoult@gmail.com>
Date: Sat, 24 Jul 2021 20:03:27 +0200
Subject: [PATCH] count matches with string manipulation: ~75% gain, 85-90%
 gain from V1

---
 day20/ex1.bash | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/day20/ex1.bash b/day20/ex1.bash
index 589dfff..d902d12 100755
--- a/day20/ex1.bash
+++ b/day20/ex1.bash
@@ -54,18 +54,20 @@ for key in "${!nums[@]}"; do
 
 done
 
-ALL=("${T[@]}" "${R[@]}" "${B[@]}" "${L[@]}" "${RT[@]}" "${RR[@]}" "${RB[@]}" "${RL[@]}")
+ALL="${T[@]} ${R[@]} ${B[@]} ${L[@]} ${RT[@]} ${RR[@]} ${RB[@]} ${RL[@]}"
+ALLSIZE=${#ALL}
+
 declare -i res=1 count
 for ((i=0; i<${#nums[@]}; ++i)); do
     count=0
 
     for t in ${T[$i]} ${R[$i]} ${B[$i]} ${L[$i]}; do
-        for s in "${ALL[@]}"; do
-            [[ $t == "$s" ]] && ((count++))
-        done
+        S=${ALL//$t}
+        # 10 is line size
+        ((count += (ALLSIZE-${#A})/10))
     done
-
-    ((count ==6)) && ((res*=${nums[$i]}))
+    # 6 is 4 for itself, + 2 for other matching
+    ((count == 6)) && ((res*=${nums[$i]}))
 done
 
 printf "%s : res=%d\n" "$CMD" "$res"