day 21 part 1 (bash)

2020/day21/ex1.bash

@@ -0,0 +1,119 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 21/game 1.
+
+CMD=${0##*/}
+shopt -s extglob
+set -o noglob
+
+declare -A I_COUNT=()
+declare -A CANBE=() I A_RULES=() FOUND=() ALL_I=()
+declare -a R
+declare -i count=0
+
+# intersect the words of 2 strings into $1
+intersect() {
+    local -n _res="$1"
+    # shellcheck disable=SC2206
+    local -a _str1=($2) _str2=($3)
+    local _i _j
+    _res=""
+    for _i in "${_str1[@]}"; do
+        for _j in "${_str2[@]}"; do
+            [[ "$_i" == "$_j" ]] && _res+=" $_i"
+        done
+    done
+    _res="${_res##*( )}"
+}
+# count words in a string and put result in $1
+count() {
+    local -n _res="$1"
+    # shellcheck disable=SC2206
+    local -a _str=($2)
+    _res=${#_str[@]}
+}
+# remove a word from a string and put result in $1
+delw() {
+    local -n _res="$1"
+    local _w=$2
+    # shellcheck disable=SC2206
+    local -a _str=($3)
+    local _i
+    _res=""
+    for _i in "${_str[@]}"; do
+        [[ $_i != "$_w" ]] && _res+=" $_i"
+    done
+    _res="${_res##*( )}"
+    _res="${_res%%*( )}"
+}
+# add a word to string $1, if not already present
+addw() {
+    local -n _s="$1"
+    # shellcheck disable=SC2206
+    local _reg="\b$2\b"
+
+    [[ "$_s" =~ $_reg ]] || _s+=" $2"
+    _s="${_s##*( )}"
+}
+
+REGEX="(.*) \(contains(.*)\)"
+while read -r line; do
+    [[ "$line" =~ $REGEX ]]
+    ingr="${BASH_REMATCH[1]}"
+    all="${BASH_REMATCH[2]}"
+    all=${all//,}
+
+    R[$count]="$ingr"
+    for ka in $all; do
+        A_RULES[$ka]+=" $count"
+        for ki in $ingr; do
+            addw CANBE[$ka] "$ki"
+            ALL_I[$ki]="$ki"
+        done
+    done
+    for ki in $ingr; do
+        (( I_COUNT[$ki]++ ))
+    done
+    ((count++))
+done
+
+declare -i solved=0 count
+declare allerg allerg1 ingred
+while ((solved==0)); do
+    solved=1
+    for allerg in "${!CANBE[@]}"; do
+        str="${CANBE[$allerg]}"
+
+        if [[ -v FOUND["$allerg"] ]]; then
+            continue
+        fi
+        for rule in ${A_RULES[$allerg]}; do
+            intersect str "${R[$rule]}" "$str"
+        done
+        CANBE[$allerg]="$str"
+
+        count count "$str"
+        ((count > 1)) && solved=0
+        if ((count==1)); then
+            word=$str #{CANBE[$allerg]}
+            FOUND[$allerg]="${CANBE[$allerg]}"
+            unset ALL_I["${CANBE[$allerg]}"]
+            for allerg1 in "${!CANBE[@]}"; do
+                if [[ "$allerg" != "$allerg1" ]]; then
+                    delw CANBE["$allerg1"]  "$word" "${CANBE[$allerg1]}"
+                fi
+            done
+            for rule in "${!R[@]}"; do
+                delw R[$rule] "$word" "${R[$rule]}"
+            done
+        fi
+    done
+done
+
+res=0
+for i in "${!ALL_I[@]}"; do
+    ((res+=${I_COUNT[$i]}))
+done
+
+printf "%s: res=%d\n" "$CMD" "$res"
+exit 0