From 10e59bd5ba9f0c2c7ab4129a024720870848433c Mon Sep 17 00:00:00 2001
From: WanCW <contact@wancw.idv.tw>
Date: Mon, 2 Dec 2024 14:53:16 +0800
Subject: [PATCH] complete day 2

---
 02-a.kts | 33 +++++++++++++++++++++++++++++++++
 02-b.kts | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 82 insertions(+)
 create mode 100644 02-a.kts
 create mode 100644 02-b.kts

diff --git a/02-a.kts b/02-a.kts
new file mode 100644
index 0000000..cabee17
--- /dev/null
+++ b/02-a.kts
@@ -0,0 +1,33 @@
+import java.util.Scanner
+
+val isSafelyIncreasing = { offset: Int -> offset in 1..3 }
+
+val isSafelyDecreasing = { offset: Int -> offset in (-3)..(-1) }
+
+fun isSafeRoute(levels: List<Int>): Boolean {
+    val levelOffsets = levels.foldIndexed(ArrayList<Int>()) { index, acc, i ->
+        if (index > 0) {
+            acc.add(i - levels[index - 1])
+        }
+        acc
+    }
+
+    return levelOffsets.all(isSafelyIncreasing) || levelOffsets.all(isSafelyDecreasing)
+}
+
+val scanner = Scanner(System.`in`)
+
+var safeCount = 0
+while (scanner.hasNextInt()) {
+    val line = scanner.nextLine()
+
+    val numbers = line.split(" ").map { it.toInt() }
+
+    if (isSafeRoute(numbers)) {
+        safeCount++
+    }
+}
+
+println(safeCount)
+
+
diff --git a/02-b.kts b/02-b.kts
new file mode 100644
index 0000000..cc6b2dd
--- /dev/null
+++ b/02-b.kts
@@ -0,0 +1,49 @@
+import java.util.Scanner
+
+val isSafelyIncreasing = { offset: Int -> offset in 1..3 }
+
+val isSafelyDecreasing = { offset: Int -> offset in (-3)..(-1) }
+
+fun isSafeRoute(levels: List<Int>): Boolean {
+    val levelOffsets = levels.foldIndexed(ArrayList<Int>()) { index, acc, i ->
+        if (index > 0) {
+            acc.add(i - levels[index - 1])
+        }
+        acc
+    }
+
+    return (levelOffsets.all(isSafelyIncreasing) || levelOffsets.all(isSafelyDecreasing))
+
+}
+
+fun isSafeRouteTolerated(levels: List<Int>): Boolean {
+    if (isSafeRoute(levels)) {
+        return true
+    }
+
+    for (skipPos in levels.indices) {
+        val skippedList = levels.slice((0)..<skipPos) + levels.slice((skipPos+1)..levels.lastIndex)
+        if (isSafeRoute(skippedList)) {
+            return true
+        }
+    }
+
+    return false
+}
+
+val scanner = Scanner(System.`in`)
+
+var safeCount = 0
+while (scanner.hasNextInt()) {
+    val line = scanner.nextLine()
+
+    val numbers = line.split(" ").map { it.toInt() }
+
+    if (isSafeRouteTolerated(numbers)) {
+        safeCount++
+    }
+}
+
+println(safeCount)
+
+