rename repo, subdir for yearly challenges

2020/day15/ex1.bash

@@ -0,0 +1,34 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 15/games 1 and 2.
+
+CMD=${0##*/}
+#shopt -s extglob
+
+declare -A prev
+declare -i cur=1 previous
+
+
+TARGET=$1
+IFS=","
+read -r line
+set -- $line
+while (($# > 0)); do
+	prev[$1]=$cur
+	((cur++))
+	shift
+done
+
+for ((previous=0; cur <= TARGET; ++cur)); do
+	if ((previous)); then
+		((diff=cur-previous-1))
+	else
+		diff=0
+	fi
+	((previous=prev[$diff]))
+	prev[$diff]=$cur
+done
+
+printf "%s : res[%d]=%d\n" "$CMD" "$TARGET" "$diff"
+
+exit 0