Two brute force methods for part 2. Slow.

2024-12-11 20:53:40 +08:00
parent d2d4bf7a64
commit 39e8e8735b
2 changed files with 110 additions and 4 deletions
--- a/2024/day-11/solution-2-2.sh
+++ b/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)"