Two brute force methods for part 2. Slow.

2024/day-11/solution-2-2.sh

@@ -0,0 +1,109 @@
+#!/usr/bin/env bash
+
+FILE=input
+ITERATIONS=75
+
+# Get max num size by squaring the largest number
+MAX_NUM_SIZE=0
+while read -r NUM
+do
+  if [[ ${#NUM} -gt $MAX_NUM_SIZE ]]
+  then
+    MAX_NUM_SIZE=${#NUM}
+  fi
+done <<< "$( < input tr " " "\n" )"
+(( MAX_NUM_SIZE*=2 ))
+
+# Just pre-compute a large number of digits
+{
+# Rule 1
+printf "0 1 \n"
+
+# Rule 2 : If even number of digits, split half half
+for (( i=10 ; i<100; i+=1 ))
+do
+  DIGIT_COUNT=${#i}
+  HALF=$(( DIGIT_COUNT / 2 ))
+  printf "%s %s %s \n" "$i" "$(( 10#${i:0:$HALF} ))" "$(( 10#${i:$HALF} ))"
+done
+for (( i=1000 ; i<10000; i+=1 ))
+do
+  DIGIT_COUNT=${#i}
+  HALF=$(( DIGIT_COUNT / 2 ))
+  printf "%s %s %s \n" "$i" "$(( 10#${i:0:$HALF} ))" "$(( 10#${i:$HALF} ))"
+done
+for (( i=100000 ; i<1000000; i+=1 ))
+do
+  DIGIT_COUNT=${#i}
+  HALF=$(( DIGIT_COUNT / 2 ))
+  printf "%s %s %s \n" "$i" "$(( 10#${i:0:$HALF} ))" "$(( 10#${i:$HALF} ))"
+done
+
+# Rule 3
+for (( i=1; i<10; i+=1 ))
+do
+  printf "%s %s \n" "$i" "$(( i * 2024 ))"
+done 
+for (( i=100; i<1000; i+=1 ))
+do
+  printf "%s %s \n" "$i" "$(( i * 2024 ))"
+done 
+for (( i=10000; i<100000; i+=1 ))
+do
+  printf "%s %s \n" "$i" "$(( i * 2024 ))"
+done 
+} | sort -n > kv-cache
+printf "Cache built. KV size: %s \n" "$( wc -l kv-cache )" 
+
+# Load cache file
+declare -A KV_CACHE
+while read -r LINE
+do
+  KV_CACHE[${LINE%% *}]="${LINE#* }"
+done < kv-cache
+
+NUM=0
+get_num () {
+
+  NUM=$1
+
+  # Rule 1 : Convert 0 to 1
+  if [[ $NUM -eq 0 ]]
+  then
+    printf "1 \n"
+    return
+  fi
+
+  # Rule 2 : If even number of digits, split half half
+  DIGIT_COUNT=${#NUM}
+  if [[ $(( DIGIT_COUNT % 2 )) -eq 0 ]]
+  then
+    HALF=$(( DIGIT_COUNT / 2 ))
+    printf "%s %s " "$(( 10#${NUM:0:$HALF} ))" "$(( 10#${NUM:$HALF} ))"
+    return
+  fi
+
+  # Rule 3 : Multiply by 2024
+  printf "%s \n" "$(( NUM * 2024 ))"
+  return
+}
+
+# Start the loop
+tr " " "\n" < "$FILE" > temp-input
+for (( i=0; i<75; i++ ))
+do
+  printf "%s Position %s\n" "$( date )" "$i"
+  while read -r NUM
+  do
+    if [[ -v ${KV_CACHE[$NUM]} ]]
+    then
+      printf "%s \n" "${KV_CACHE[$NUM]}"
+    else
+      get_num "$NUM"
+    fi
+  done < temp-input |
+  tr " " "\n" |
+  grep -Eo '[0-9]*' | 
+  sponge temp-input
+done
+printf "Final count: %s\n" "$(wc -l < temp-input)"

2024/day-11/solution-2.sh

@@ -55,13 +55,11 @@ blink_rocks () {
   #printf "\n" >&2
 }
 
-#FINAL_LIST=()
-# Keeps track of 
 read -r -a FINAL_LIST <<< "$( printf "%s " "${ROCK_LIST[@]}" )"
 POSITION=0
 while [[ $POSITION -lt $BLINK_NUM ]]
 do
-  printf "%s Working on position %s\n" "$( date )" "$POSITION"
+  printf "%s Starting position %s, current len: %s, kv size: %s\n" "$( date )" "$POSITION" "${#FINAL_LIST[@]}" "${#KV_CACHE[@]}"
   INTER_LIST_1=()
   # Essentially move $DEPTH steps at a time
   for ROCK in "${FINAL_LIST[@]}"
@@ -93,7 +91,6 @@ do
   # All rocks are calculated $DEPTH ahead
   (( POSITION+=DEPTH ))
 done
-#FINAL_LIST+=( "${BLINKED_ROCKS[@]}" )
 
 # Dump KV cache for debugging
 if [[ $DUMP_KV_CACHE -eq 0 ]]