AoC 2025 Day 3 - bash

Author: pareronia

README.md

@@ -10,7 +10,7 @@
 | ---| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
 | python3 | [✓](src/main/python/AoC2025_01.py) | [✓](src/main/python/AoC2025_02.py) | [✓](src/main/python/AoC2025_03.py) |  |  |  |  |  |  |  |  |  |
 | java | [✓](src/main/java/AoC2025_01.java) | [✓](src/main/java/AoC2025_02.java) |  |  |  |  |  |  |  |  |  |  |
-| bash | [✓](src/main/bash/AoC2025_01.sh) | [✓](src/main/bash/AoC2025_02.sh) |  |  |  |  |  |  |  |  |  |  |
+| bash | [✓](src/main/bash/AoC2025_01.sh) | [✓](src/main/bash/AoC2025_02.sh) | [✓](src/main/bash/AoC2025_03.sh) |  |  |  |  |  |  |  |  |  |
 <!-- @END:ImplementationsTable:2025@ -->
 
 ## 2024

src/main/bash/AoC2025_03.sh

@@ -0,0 +1,61 @@
+#!/bin/bash
+#
+# Advent of Code 2025 Day 3
+#
+
+year=2025
+day=03
+
+solve_line() {
+    local line="$1"
+    local -i digits="$2"
+    local -i pos=0
+
+    for ((i = digits; i > 0; i--)); do
+        best=0
+        for ((j = pos; j < ${#line} - i + 1; j++)); do
+            if ((${line:j:1} > best)); then
+                best=${line:j:1}
+                ((pos = j + 1))
+            fi
+        done
+        echo -n "$best"
+    done
+    return 0
+}
+
+solve() {
+    local -i ans=0
+    while read -r line || [ -n "$line" ]; do
+        ((ans += $(solve_line "$line" "$2")))
+    done < "$1"
+    echo "$ans"
+    return 0
+}
+
+part1() {
+    solve "$1" 2
+    return 0
+}
+
+part2() {
+    solve "$1" 12
+    return 0
+}
+
+tests() {
+    # shellcheck disable=SC2034
+    {
+        sample=(
+            "987654321111111"
+            "811111111111119"
+            "234234234234278"
+            "818181911112111"
+        )
+    }
+
+    TEST part1 sample 357
+    TEST part2 sample 3121910778619
+}
+
+source "$(dirname "$0")/aoc_main.sh"