Add Day 3 Problem 1

3/1/solution.sh

@@ -0,0 +1,76 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+if [[ "${TRACE-0}" == "1" ]]; then
+  set -o xtrace
+fi
+
+cd "$(dirname "$0")"
+
+LINES=$(wc -l < "$1")
+COLUMNS=140
+mapfile -t -O 1 INPUT < "$1"
+declare -a valid_numbers
+
+find_numbers ()
+{
+  # Find and append valid numbers to array.
+  for ((line=1; line<=LINES; line++)); do
+    for ((column=1; column<=COLUMNS; column++)); do
+      if [[ $(arr "${line}" $((column-1))) =~ ^[0-9]$ ]]; then
+        continue # not start of number
+      else
+        local number='' length=0
+        for ((i=column; ; i++)); do # find length
+          if [[ $(arr "${line}" "${i}") =~ ^[0-9]$ ]]; then
+            ((length++)) || true
+          else
+            break
+          fi
+        done
+        [[ length -gt 0 ]] || continue # not a number
+        for ((i=0; i<length; i++)); do # get number
+          number+="$(arr "${line}" $((column+i)))"
+        done
+        declare -a to_check=("${line},$((column-1))" "${line},$((column+length))") # before and after
+        for ((i=column-1; i<=column+length; i++)); do
+          to_check+=("$((line-1)),${i}") # above
+          to_check+=("$((line+1)),${i}") # below
+        done
+        for ((i=0; i<${#to_check[@]}; i++)); do
+          if [[ $(arr "${to_check[i]%,*}" "${to_check[i]#*,}") =~ ^(\$|\*|/|=|\+|-|#|@|&|%)$ ]]; then
+            valid_numbers+=("${number}")
+            break
+          fi
+        done
+      fi
+    done
+  done
+}
+
+arr ()
+{
+  # Usage: arr LINE COLUMN
+  line="$1"
+  column=$(($2-1))
+  if ((line<=0)) || ((line>LINES)) || ((column<0)); then
+    echo -n ''
+  else
+    echo -n "${INPUT[${line}]:${column}:1}"
+  fi
+}
+
+
+main ()
+{
+  find_numbers
+  sum=0
+  for number in "${valid_numbers[@]}"; do
+    sum=$((sum+number))
+  done
+  echo $sum
+}
+
+main