From 7d7b3ee15db979d19133e54c59d340a5941452f0 Mon Sep 17 00:00:00 2001
From: mappu <mappu04@gmail.com>
Date: Sun, 19 May 2024 18:10:39 +1200
Subject: [PATCH] initial commit

---
 countdown.sh | 25 ++++++++++++++++
 solve.sh     | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)
 create mode 100755 countdown.sh
 create mode 100755 solve.sh

diff --git a/countdown.sh b/countdown.sh
new file mode 100755
index 0000000..4321466
--- /dev/null
+++ b/countdown.sh
@@ -0,0 +1,25 @@
+#!/bin/bash
+
+set -eu
+
+randn() {
+	# 1-ARG inclusive
+	seq 1 $1 | shuf | head -n1
+}
+
+big() {
+	echo '10 25 50 75 100' | tr ' ' $'\n' | shuf | head -n1
+}
+
+small() {
+	seq 1 10 | shuf | head -n1
+}
+
+main() {
+	printf "Target: %03d\n" $(randn 999)
+	printf "Numbers: %d %d %d %d %d %d\n" \
+		`big` `big` `small` `small` `small` `small`
+}
+
+main "$@"
+
diff --git a/solve.sh b/solve.sh
new file mode 100755
index 0000000..e764fc6
--- /dev/null
+++ b/solve.sh
@@ -0,0 +1,80 @@
+#!/bin/bash
+
+set -eu
+
+main() {
+	local targ="$1"
+	shift
+	local vals="$@"
+
+	#echo "solving for $targ using $vals"
+
+	for v in $vals ; do
+		if [[ $v == $targ ]] ; then
+			echo won
+			return 0
+		fi
+	done
+
+	if [[ $# < 2 ]] ; then
+		#echo "out of options"
+		return 1
+	fi
+
+	declare -i i
+	declare -i j
+	declare -i k
+	for (( i=1 ; i <= $# ; i++ )) ; do
+		for (( j=$i ; j <= $# ; j++ )) ; do
+			if [[ $i == $j ]] ; then
+				continue
+			fi
+
+			declare -i iv=${!i}
+			declare -i jv=${!j}
+
+			local others=''
+			for (( k=1 ; k <= $# ; k++ )) ; do
+				if [[ $i == $k || $j == $k ]] ; then
+					continue
+				fi
+				local kv=${!k}
+				others="$others $kv"
+			done
+
+			if main $targ $others $(($iv + $jv)) ; then
+				echo $iv + $jv = $(($iv + $jv))
+				return 0
+			fi
+			if main $targ $others $(($jv - $iv)) ; then
+				echo $jv - $iv = $(($jv - $iv))
+				return 0
+			fi
+			if main $targ $others $(($iv - $jv)) ; then
+				echo $iv - $jv = $(($iv - $jv))
+				return 0
+			fi
+			if main $targ $others $(($iv * $jv)) ; then
+				echo $iv x $jv = $(($iv * $jv))
+				return 0
+			fi
+
+			if [[ $jv != 0 && $(( $iv % $jv )) == 0 ]] && \
+			   main $targ $others $(($iv / $jv)) ; then
+				echo $iv / $jv = $(($iv / $jv))
+				return 0
+			fi
+			if [[ $iv != 0 && $(( $jv % $iv )) == 0 ]] && \
+			   main $targ $others $(($jv / $iv)) ; then
+				echo $jv / $iv = $(($jv / $iv))
+				return 0
+			fi
+		done
+	done
+
+	#echo "no solution"
+	return 1
+}
+
+main "$@"
+