From 8fdd92b15a1295609bbcf9afa7ed4821820bf803 Mon Sep 17 00:00:00 2001
From: Sven Weidauer <sven@5sw.de>
Date: Sat, 10 Dec 2022 15:28:16 +0100
Subject: [PATCH] 2022 Day 8 Part 1

---
 2022/.gitignore |  1 +
 2022/day8.kt    | 83 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)
 create mode 100644 2022/day8.kt

diff --git a/2022/.gitignore b/2022/.gitignore
index 63ff173..708db1e 100644
--- a/2022/.gitignore
+++ b/2022/.gitignore
@@ -1 +1,2 @@
 *.input
+*.jar
diff --git a/2022/day8.kt b/2022/day8.kt
new file mode 100644
index 0000000..a6621f7
--- /dev/null
+++ b/2022/day8.kt
@@ -0,0 +1,83 @@
+// kotlinc  day8.kt -include-runtime -d day8.jar && java -jar day8.jar
+
+import java.io.File
+
+class Matrix(
+    private val data: List<String>
+) {
+    val width = data[0].count()
+    val height = data.count()
+
+    operator fun get(x: Int, y: Int): Int {
+        check(x in 0 until width && y in 0 until height) { "Out of bounds" }
+        
+        return data[y][x].code - '0'.code
+    }
+    
+    fun column(x: Int): Sequence<Int> {
+        check(x in 0 until width) { "Out of bounds" }
+        return sequence {
+            for (y in 0 until height) yield(get(x, y))
+        }
+    }
+    
+    fun row(y: Int): Sequence<Int> {
+        check(y in 0 until height) { "Out of bounds" }
+        return sequence {
+            for (x in 0 until width) yield(get(x, y))
+        }
+    }
+    
+    fun reverseColumn(x: Int): Sequence<Int> {
+        check(x in 0 until width) { "Out of bounds" }
+        return sequence {
+            for (y in height - 1 downTo 0) yield(get(x, y))
+        }
+    }
+    
+    fun reverseRow(y: Int): Sequence<Int> {
+        check(y in 0 until height) { "Out of bounds" }
+        return sequence {
+            for (x in width - 1 downTo 0) yield(get(x, y))
+        }
+    }
+}
+
+fun Sequence<Int>.findVisibles(): Set<Int> {
+    var max = -1
+    var result = mutableSetOf<Int>()
+    
+    for ((index,element) in withIndex()) {
+        if (element > max) {
+            max = element
+            result.add(index)
+            
+            if (max == 9) break
+        }
+    }
+    
+    return result
+}
+
+fun main() {
+    val data = File("day8.input").useLines { lines -> 
+        lines.toList()
+    }
+
+    val matrix = Matrix(data)
+    
+    
+    val visible = mutableSetOf<Pair<Int, Int>>()
+
+    for (row in 0 until matrix.height) {
+        visible.addAll(matrix.row(row).findVisibles().map { it to row })
+        visible.addAll(matrix.reverseRow(row).findVisibles().map { matrix.width - 1 - it to row })
+    }
+    
+    for (col in 0 until matrix.width) {
+        visible.addAll(matrix.column(col).findVisibles().map { col to it })
+        visible.addAll(matrix.reverseColumn(col).findVisibles().map { col to matrix.height - 1 - it })
+    }
+    
+    println("Part 1: ${visible.count()}")
+}