Add 2023 Day 01 Part 2 solution

palinkiewicz · palinkiewicz · commit 5276a036b1e7 · 2023-12-03T18:44:06.000+01:00
diff --git a/adventofcode2023/Day01.kt b/adventofcode2023/Day01.kt
@@ -2,14 +2,48 @@ package adventofcode2023
 
 import java.io.File
 
-fun part1(file: File) {
-    println(file.readLines().sumOf { line ->
+fun part1(inputs: List<String>) {
+    println(inputs.sumOf { line ->
         val digits = line.filter { char -> char.isDigit() }
         digits.first().digitToInt() * 10 + digits.last().digitToInt()
     })
 }
 
-fun main(args: Array<String>) {
-    val inputs = File("resources/adventofcode2023/Day01.txt")
+fun part2(inputs: List<String>) {
+    val digits = setOf(
+        Pair("one", '1'),
+        Pair("two", '2'),
+        Pair("three", '3'),
+        Pair("four", '4'),
+        Pair("five", '5'),
+        Pair("six", '6'),
+        Pair("seven", '7'),
+        Pair("eight", '8'),
+        Pair("nine", '9')
+    )
+
+    fun findDigit(line: String, indices: IntProgression = line.indices): Int {
+        for (i in indices) {
+            for (digit in digits) {
+                if ((line.length >= i + digit.first.length
+                            && line.substring(i, i + digit.first.length) == digit.first)
+                    || line[i] == digit.second
+                ) {
+                    return digit.second.digitToInt()
+                }
+            }
+        }
+
+        return 0
+    }
+
+    println(inputs.sumOf { line ->
+        findDigit(line) * 10 + findDigit(line, line.indices.reversed())
+    })
+}
+
+fun main() {
+    val inputs = File("resources/adventofcode2023/Day01.txt").readLines()
     part1(inputs)
+    part2(inputs)
 }
