Add gradle task to generate next day

build.gradle.kts

@@ -16,4 +16,37 @@ tasks {
     wrapper {
         gradleVersion = "7.6"
     }
+
+    task("generateNextDay") {
+        doLast {
+            val prevDayNum = fileTree("$projectDir/src").matching {
+                include("Day*.kt")
+            }.maxOf {
+                val (prevDayNum) = Regex("Day(\\d\\d)").find(it.name)!!.destructured
+                prevDayNum.toInt()
+            }
+            val newDayNum = String.format("%02d", prevDayNum + 1)
+            File("$projectDir/src", "Day$newDayNum.kt").writeText(
+                """
+fun main() {
+    fun part1(input: List<String>): Int {
+        return 0
+    }
+
+    fun part2(input: List<String>): Int {
+        return 0
+    }
+
+    // test if implementation meets criteria from the description, like:
+    val testInput = readInput("resources/Day${newDayNum}_test")
+    check(part1(testInput) == 0)
+
+    val input = readInput("resources/Day$newDayNum")
+    println(part1(input))
+    println(part2(input))
+}
+"""
+            )
+        }
+    }
 }