Add Day 4

4/2/solution.sh

@@ -0,0 +1,54 @@
+#!/usr/bin/env bash
+
+set -o errexit
+set -o nounset
+set -o pipefail
+if [[ "${TRACE-0}" == "1" ]]; then
+  set -o xtrace
+fi
+
+cd "$(dirname "$0")"
+
+mapfile -t -O 1 INPUT < "input.txt"
+CARDS="${#INPUT[@]}"
+
+run_cards ()
+{
+  # Receives space separated list of cards I have.
+  for ((x=1; x<=CARDS; x++)); do
+    declare -a winning=() mine=()
+    declare -i matching=0
+    declare -i count="${hand[$x]}"
+    stripped=$(sed 's/Card\s\{1,3\}[0-9]\{1,3\}: //' <<< "${INPUT[$x]}")
+    winning+=($(cut -d '|' -f 1 <<< "${stripped}"))
+    mine+=($(cut -d '|' -f 2 <<< "${stripped}"))
+    for number in "${mine[@]}"; do
+      for w in "${winning[@]}"; do
+        if [[ ${number} -eq ${w} ]]; then
+          matching=$((matching+1))
+          break
+        fi
+      done
+    done
+    for ((i=1; i<=matching; i++)); do
+      hand[$((x+i))]=$((${hand[$((x+i))]}+count))
+    done
+  done
+}
+
+main ()
+{
+  declare -i sum=0
+  declare -A hand=()
+  for ((z=1; z<=CARDS; z++)); do
+    hand+=([${z}]=1)
+  done
+  run_cards "${hand[@]}"
+  for ((z=1; z<=CARDS; z++)); do
+    echo "card $z: ${hand[$z]}"
+    sum=$((sum+${hand[$z]}))
+  done
+  echo "${sum}"
+}
+
+main "$@"