120 lines
2.6 KiB
Bash
Executable File
120 lines
2.6 KiB
Bash
Executable File
#!/bin/bash
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#
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# ex1.bash: Advent2020 game, day 18/game 1.
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CMD=${0##*/}
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shopt -s extglob
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set -o noglob
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declare -a STACK=()
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declare -a LINE=()
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function enqueue() {
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local -n stack="$1"
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local var="$2"
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stack=("$var" "${stack[@]}")
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}
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function dequeue() {
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# shellcheck disable=2178
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local -n stack="$1"
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local -n var="$2"
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local last=$((${#stack[@]} - 1))
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var=${stack[$last]}
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unset 'stack[$last]'
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stack=( "${stack[@]}" ) # pack
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}
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function eval_op() {
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local -n lvalop="$1" loptop="$2"
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local v v1 v2 op res=-1
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while ((${#lvalop[@]} > 1)); do
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dequeue lvalop v1
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dequeue lvalop v2
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dequeue loptop op
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v=$((v1 $op v2))
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enqueue lvalop "$v"
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((res++))
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done
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return $res
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}
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function find_paren() {
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local -n expr_="$1"
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local -n var_="$2"
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local -i i
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local k val
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var_=-1
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for k in "${!expr_[@]}"; do
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val=${expr_[$k]}
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[[ $val == '(' ]] && i="$k"
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if [[ $val == ')' ]]; then
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var_="$i"
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break
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fi
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done
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}
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function eval_expr() {
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local -n gstack="$1"
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#local -n expr=(${LINE[@]}) #"$3"
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local -i cur="$2" val len=${#LINE[@]}
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local op
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local -a lstack=() lop=() lstack_=() LINE_=()
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while ((cur < len)); do
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symbol=${LINE[$cur]}
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case "$symbol" in
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+([0-9]))
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enqueue lstack "${LINE[$cur]}"
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unset 'LINE[$cur]'
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;;
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\))
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break
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;;
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+([\+\*]))
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enqueue lop "${LINE[$cur]}"
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unset 'LINE[$cur]'
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;;
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*)
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exit 1
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;;
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esac
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eval_op lstack lop
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((cur++))
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done
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dequeue lstack val
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LINE[$cur]="$val"
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LINE=(${LINE[@]}) # pack
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}
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declare -i res=0 num=0 paren=0
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while read -r line; do
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# cleanup input line, force split around operators and parens
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line=${line//\*/ * }
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line=${line//+/ + }
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line=${line//-/ - }
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line=${line//\// \/ }
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line=${line//\(/ \( }
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line=${line//\)/ \) }
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LINE=($line)
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paren=0
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while ((${#LINE[@]} > 1 && paren >= 0)); do
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find_paren LINE paren
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if (( paren >= 0 )); then
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unset LINE[$paren]
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LINE=(${LINE[@]}) # pack
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eval_expr STACK "$paren"
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LINE=(${LINE[@]}) # pack
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fi
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done
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if ((${#LINE[@]} > 1)); then
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eval_expr STACK 0
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fi
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((res+=${LINE[0]}))
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done
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printf "%s : res=%d\n" "$CMD" "$res"
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exit 0
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