first pass with demo input

day/01/demo_input.txt

@@ -0,0 +1,6 @@
+3   4
+4   3
+2   5
+1   3
+3   9
+3   3

day/01/part1.sh

@@ -0,0 +1,64 @@
+#! /bin/bash
+
+#set -x
+
+FILE_IN="${1}"
+
+left_list=()
+right_list=()
+
+while read -r l; do
+  echo "reading new line [$l]"
+  IFS=" "
+  read -ra line_split <<< "${l}"
+  unset IFS
+  echo "first number [${line_split[0]}]"
+  echo "second number [${line_split[1]}]"
+  left_list+=("${line_split[0]}")
+  right_list+=("${line_split[1]}")
+done <"$FILE_IN"
+
+echo "${left_list[@]}"
+echo "${right_list[@]}"
+
+if [[ ${#left_list[@]} -ne ${#right_list[@]} ]]; then
+  echo "arrays dont match, wtf?"
+  exit 1
+else
+  echo "length of lists ${#left_list[@]}"
+fi
+
+echo "sorting time"
+
+IFS=$'\n'
+mapfile sorted_left_list <<<"$(sort <<<"${left_list[*]}")"
+mapfile sorted_right_list <<<"$(sort <<<"${right_list[*]}")"
+unset IFS
+
+echo "${sorted_left_list[@]}"
+echo "${sorted_right_list[@]}"
+
+sorted_list_diff=()
+
+echo "adding time"
+
+for i in "${!sorted_left_list[@]}"; do
+  echo "left index: ${i} value: ${sorted_left_list[$i]}"
+  echo "right index: ${i} value: ${sorted_right_list[$i]}"
+
+  i_diff=$((${sorted_left_list[$i]}-${sorted_right_list[$i]}))
+
+  echo "diff ${i_diff}"
+
+  sorted_list_diff+=("${i_diff#-}")
+done
+
+echo "${sorted_list_diff[@]}"
+
+final_out=0
+
+for v in "${sorted_list_diff[@]}"; do
+  final_out=$((final_out + v))
+done
+
+echo "final output: ${final_out}"