day11

day11.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+unset PATH
+readonly PATH
+source ./utils/main.sh
+source ./utils/array.sh
+
+count_after_blinks() {
+  local blinks="$1"
+  local -A stones=() new_stones=()
+
+  for stone in "${@:2}"; do stones["$stone"]=1; done
+
+  for ((n = 0; n < blinks; n++)); do
+    for stone in "${!stones[@]}"; do
+      if ((stone == 0)); then
+        new_stones[1]="$((${new_stones[1]:-0} + stones["$stone"]))"
+      elif ((${#stone} % 2 == 0)); then
+        left="${stone::"$((${#stone} / 2))"}"
+        right="${stone:"$((${#stone} / 2))"}"
+        right="$((10#"$right"))"
+
+        new_stones["$left"]="$((${new_stones["$left"]:-0} + stones["$stone"]))"
+        new_stones["$right"]="$((${new_stones["$right"]:-0} + stones["$stone"]))"
+      else
+        new_stones["$((stone * 2024))"]="$((${new_stones["$((stone * 2024))"]:-0} + stones["$stone"]))"
+      fi
+      stones["$stone"]=0
+    done
+
+    local old new
+    old="$(declare -p stones)"
+    new="$(declare -p new_stones)"
+    eval "${old/stones/new_stones}"
+    eval "${new/new_stones/stones}"
+  done
+
+  array.sum stones
+}
+
+p1() {
+  local input="$1"
+  local -a stones
+
+  read -ra stones <<<"$input"
+  count_after_blinks 25 "${stones[@]}"
+}
+
+p2() {
+  local input="$1"
+  local -a stones
+
+  read -ra stones <<<"$input"
+  count_after_blinks 75 "${stones[@]}"
+}
+
+main "$@"