rename repo, subdir for yearly challenges

2020/day12/ex2.bash

@@ -0,0 +1,48 @@
+#!/bin/bash
+#
+# ex2.bash: Advent2020 game, day 12/game 2.
+
+CMD=${0##*/}
+shopt -s extglob
+
+declare -i X=0 Y=0 WX=10 WY=1
+declare -i DIRECTION=90
+
+while read -r line; do
+	C=${line:0:1}
+	A=${line:1}
+	DIRECTION=0
+
+	case "$C" in
+		R) ((DIRECTION=A))
+		   ;;
+		L) ((DIRECTION=360-A))
+		   ;;
+		F) for ((i=0; i<A; ++i)); do
+			   ((X+=WX))
+			   ((Y+=WY))
+		   done
+		   ;;
+		N) ((WY+=A))
+		   ;;
+		S) ((WY-=A))
+		   ;;
+		E) ((WX+=A))
+		   ;;
+		W) ((WX-=A))
+		   ;;
+	esac
+	if ((DIRECTION > 0)); then
+		for ((i=90; i<=DIRECTION; i+=90)); do
+			((tx=WY))
+			((WY=-WX))
+			((WX=tx))
+		done
+	fi
+done
+
+((X<0)) && ((X=-X))
+((Y<0)) && ((Y=-Y))
+printf "%s : res=%d\n" "$CMD" $((X+Y))
+
+exit 0