rename repo, subdir for yearly challenges

2020/day08/ex2.bash

@@ -0,0 +1,78 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 8/game 2.
+
+CMD=${0##*/}
+shopt -s extglob
+
+declare -a PRG=()
+declare -i ARG=()
+
+function run() {
+	local -i arg cur=0 res=0 size=$1
+	local instr
+	local -a steps=()
+
+	while ((cur < size)) && [[ ${steps[$cur]} != 1 ]]; do
+		instr=${PRG[$cur]}
+		arg=${ARG[$cur]}
+		steps[$cur]=1
+		case "$instr" in
+			acc)
+				((res += arg))
+				((cur++))
+				;;
+			nop)
+				((cur++))
+				;;
+			jmp)
+				((cur += arg))
+				;;
+		esac
+	done
+	echo $res
+	return $((cur < size))
+}
+
+function print_prog()
+{
+	local -i i
+	for ((i=0; i<${#PRG[@]}; ++i)); do
+		printf "%03d : [%s][%3d]\n" "$i" "${PRG[$i]}" "${ARG[$i]}"
+	done
+}
+
+declare -i i=0
+while read -r instr arg; do
+	PRG[$i]=$instr
+	ARG[$i]=$arg
+	((i++))
+done
+
+lastchanged=-1
+savstep=""
+while true; do
+	res=$(run $i) && break
+
+	if ((lastchanged >= 0)); then
+		PRG[$lastchanged]="$savstep"
+	fi
+	((lastchanged++))
+	while ((lastchanged <= PRGSIZE)) && [[ ${PRG[$lastchanged]} == acc ]]; do
+		((lastchanged++))
+	done
+
+	savstep=${PRG[$lastchanged]}
+	case $savstep in
+		jmp)
+			PRG[$lastchanged]="nop"
+			;;
+		nop)
+			PRG[$lastchanged]="jmp"
+			;;
+	esac
+done
+
+printf "%s : res:%d\n" "${CMD}" "$res"
+
+exit 0