more debug

day/02/demo_2_input.txt

@@ -7,3 +7,4 @@
 9 8 2 7
 9 8 7 1
 9 4 10 11
+9 4 10 11 10

day/02/part2.sh

@@ -93,7 +93,11 @@ while read -r l; do
       if [[ "${idx}" -eq 1 ]]; then
         # we may have to re-calculate is_up_down!
         is_up_down="$((line_split[2] - line_split[0]))"
+        echo "allowing flip up/down"
       fi
+      echo "-------------------"
+      echo "allowing 1 failure!"
+      echo "-------------------"
     else
       # we skip the re-assign once to 'skip' a number
       prev_val=$v
@@ -105,7 +109,7 @@ while read -r l; do
   else
     echo "final check safe"
   fi
-
+  echo ""
   safe_count=$((safe_count + is_safe))
 done <"$FILE_IN"