bash/day1.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+firstDigits() {
+    sed 's|^[^0-9]*\([0-9]\).*|\1|'
+}
+
+lastDigits() {
+    sed 's|^.*\([0-9]\)[^0-9]*$|\1|'
+}
+
+sumTensDigits() {
+    echo $(("$(xargs -I '{}' echo '{} * 10 +') 0"))
+}
+
+sumOnesDigits() {
+    echo $(("$(xargs -I '{}' echo '{} +') 0"))
+}
+
+detectDigits() {
+    sed '
+         s|zero|0|g;
+
+         s|twone|2|g;
+         s|one|1|g;
+
+         s|eightwo|8|g;
+         s|two|2|g;
+
+         s|eighthree|8|g;
+         s|three|3|g;
+
+         s|four|4|g;
+         s|five|5|g;
+         s|six|6|g;
+         s|seven|7|g;
+
+         s|nineight|9|g;
+         s|eight|8|g;
+
+         s|nine|9|g
+         '
+}
+
+detectReverseDigits() {
+    sed '
+         s|enorez|1|g
+         s|orez|0|g;
+
+         s|thgieno|8|g;
+         s|eno|1|g;
+
+         s|owt|2|g;
+
+         s|thgieerht|8|g;
+         s|eerht|3|g;
+
+         s|ruof|4|g;
+
+         s|thgievif|8|g;
+         s|evif|5|g;
+
+         s|xis|6|g;
+
+         s|enineves|9|g
+         s|neves|7|g;
+
+         s|thgie|8|g;
+
+         s|enin|9|g
+         '
+}
+
+part1 () {
+    local input=$(cat)
+    local tensSum=$(<<< "$input" firstDigits | sumTensDigits)
+    local onesSum=$(<<< "$input" lastDigits | sumOnesDigits)
+    echo $(("$tensSum + $onesSum"))
+}
+
+part2 () {
+    local input=$(cat)
+    local tensSum=$(<<< "$input" detectDigits | firstDigits | sumTensDigits)
+    local onesSum=$(<<< "$input" rev | detectReverseDigits | firstDigits | sumOnesDigits)
+    echo $(("$tensSum + $onesSum"))
+}
+
+main () {
+    local input=$(cat)
+    echo "Answer 1: $(part1 <<< "$input")"
+    echo "Answer 2: $(part2 <<< "$input")"
+}
+
+main