18: Fix part 1 and improve speed

Part 1 was giving the wrong result because of globbing
Rewritten to use bash regex instead of recursive grep -o (5-6x speedup)
Part 2 made a fast one-liner

Author: einarjon

18.sh

@@ -1,6 +1,6 @@
 #! /usr/bin/env bash
 IFS=$'\n'
-set -f # globbing off
+set -o noglob
 A=($(< ${1:-18.txt}))
 c() {
     local i sum=0 op='+'
@@ -11,34 +11,20 @@ c() {
             sum=$((sum$op$i))
         fi
     done
-    #echo "c:  ${@//[()]} =  $sum " >&2
+    #echo "c: ${*//[()]} = $sum " >&2
     echo ${sum}
 }
 
-r() { # TODO: Try bash regex for speed
-    local line="$1" k n total
-    local inner=($(echo "$line"| grep -o  "([^()]*)"))
-    while [[ "${#inner[@]}" != 0 ]]; do
-        for k in "${inner[@]}"; do
-            n=$(c "$k")
-            line="${line/$k/$n}"
-        done
-        line=$(r "$line")
-        inner=($(echo "$line"| grep -o  "([^()]*)"))
+IFS=$' \t\n'
+regex="\([^()]*\)"
+sum=""
+for line in "${A[@]}"; do
+    while [[ "$line" =~ $regex ]]; do
+        k=${BASH_REMATCH[0]}
+        n=$(c "$k")
+        line="${line/${k//\*/\\*}/$n}" # stupid globbing
     done
-    total=$(c "$line")
-    echo $total
-}
-B=()
-for i in "${A[@]}"; do
-    B+=($(r "$i"))
+    sum+=+$(c "$line")
 done
-sum=$(echo ${B[*]} | tr ' ' '+')
 echo "18A: $((sum))"
-sum=""
-for i in "${A[@]}"; do
-    k="(${i//\*/)*(})"
-    sum+="+$((k))"
-done
-IFS='+'
-echo "18B: $(($sum))"
+echo "18B: $(($(printf "+(%s)" "${A[@]//\*/)*(}")))"

README.md

@@ -91,7 +91,7 @@ Description of what I'm doing. Contains spoilers....
 
 ### 18.sh
  Have to turn glob off, or \* will be replaced with all files in directory.
- 1. Recursive grep to find a brackets that don't contain inner brackets. Calculate those. Replace the whole bracket with calculated result. Repeat. Slow but works.
+ 1. Bash regex to find a bracket that doesn't contain inner brackets. Calculate that. Replace the whole bracket with result. Repeat until no brackets remain. Slow, but faster than grep -o.
  2. Just replace "\*" with ")\*(" to change the precedence. Add "(" and ")" to the ends to close off the brackets.
 
 ### 19.sh