Broken part 2

2024/day-9/solution-2.sh

@@ -0,0 +1,100 @@
+#!/usr/bin/env bash
+
+FILE=input
+# Sparse sequence
+read -r -a SPARSE_ARRAY <<< "$(
+  INDEX=0
+  FILE_ID=0
+  while read -r CHAR
+  do
+    if [[ $(( INDEX % 2 )) -eq 0 ]]
+    then
+      for (( i=1; i<=CHAR; i++ )) do printf "%s " "$FILE_ID"
+      done
+      (( FILE_ID++ ))
+    else
+      for (( i=1; i<=CHAR; i++ ))
+      do
+        printf ". "
+      done
+    fi
+    (( INDEX++ ))
+  done <<< "$( sed -E 's/(.)/\1\n/g' "$FILE" | grep -v '^$' )"
+)"
+printf "%s" "${SPARSE_ARRAY[@]}"
+printf "\n"
+printf "Sparse array len: %s\n" "${#SPARSE_ARRAY[@]}"
+SHADOW_ARRAY=( "${SPARSE_ARRAY[@]}" )
+
+# Start by working backwards
+j=$(( ${#SPARSE_ARRAY[@]} - 1 )) # Moveable index since file blocks jump
+k=0 # SHADOW_ARRAY cursor
+while [[ $j -ge 0 ]]
+do
+  if [[ ${SPARSE_ARRAY[j]} != '.' ]] 
+  then
+
+    # Get file size
+    FILE_SIZE=0
+    ID=${SPARSE_ARRAY[j]}
+    while [[ ${SPARSE_ARRAY[j]} == "$ID" ]]
+    do
+      (( FILE_SIZE++ ))
+      (( j-- ))
+    done
+    printf "File ID: %s, File size: %s\n" "$ID" "$FILE_SIZE" 2>&1
+
+    # Search for available contiguous space
+    # Search from start until the file itself
+    k=0
+    while [[ $k -lt $(( j - FILE_SIZE )) ]] 
+    do
+      CONT_SPACE=0
+
+      # Skip ahead until first match of space
+      while [[ ${SHADOW_ARRAY[k]} != "." ]]
+      do
+        (( k++ ))
+      done
+
+      # Space found, now get contiguous length
+      while [[ ${SHADOW_ARRAY[k]} == '.' ]]
+      do
+        (( CONT_SPACE++ ))
+        (( k++ ))
+      done
+      
+      # Space length is ok, can proceed
+      if [[ $FILE_SIZE -le $CONT_SPACE ]] ;then break; fi
+    done
+
+    # Can proceed
+    if [[ $FILE_SIZE -le $CONT_SPACE ]]
+    then
+      # Move the file to the contiguous space
+      (( k-= CONT_SPACE ))
+      while [[ $FILE_SIZE -gt 0 ]]
+      do
+        SHADOW_ARRAY[k]=$ID
+        SHADOW_ARRAY[j+FILE_SIZE]='.'
+	(( k++ ))
+        (( FILE_SIZE-- ))
+      done
+    else
+      # Skip the file
+      continue
+    fi
+  else
+    (( j-- ))
+  fi
+done
+printf "%s" "${SHADOW_ARRAY[@]}"
+printf "\n"
+
+# Generate checksum for sparse array
+CHECKSUM=0
+for (( i=0; i<${#SHADOW_ARRAY[@]}; i++ ))
+do
+  if [[ ${SHADOW_ARRAY[i]} != "." ]] ;then (( CHECKSUM += i * SHADOW_ARRAY[i] )); fi
+done
+printf "%s" "$CHECKSUM"