From d0e01148ffb4558a7ed4d2dc2cd284e675f1ca76 Mon Sep 17 00:00:00 2001
From: Sugui <anaisusg@gmail.com>
Date: Wed, 6 Dec 2023 10:25:00 +0100
Subject: [PATCH] day 6, optimized :3

---
 resources/input06.txt              |  2 +
 src/main/java/sugui/Day06.java     | 69 ++++++++++++++++++++++++++++++
 src/test/java/sugui/Day06Test.java | 33 ++++++++++++++
 3 files changed, 104 insertions(+)
 create mode 100644 resources/input06.txt
 create mode 100644 src/main/java/sugui/Day06.java
 create mode 100644 src/test/java/sugui/Day06Test.java

diff --git a/resources/input06.txt b/resources/input06.txt
new file mode 100644
index 0000000..33de0fa
--- /dev/null
+++ b/resources/input06.txt
@@ -0,0 +1,2 @@
+Time:        52     94     75     94
+Distance:   426   1374   1279   1216
diff --git a/src/main/java/sugui/Day06.java b/src/main/java/sugui/Day06.java
new file mode 100644
index 0000000..7f7e531
--- /dev/null
+++ b/src/main/java/sugui/Day06.java
@@ -0,0 +1,69 @@
+package sugui;
+
+import java.io.IOException;
+import java.lang.reflect.Array;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+public class Day06 {
+
+    public static Path inputPath = Paths.get("resources/input06.txt");
+
+    private record Race(long time, long bestMark) {
+    }
+
+    public static void main(String[] args) throws IOException {
+        var input = Files.readString(inputPath);
+        var firstResult = getFirstPuzzleResult(input);
+        var secondResult = getSecondPuzzleResult(input);
+        System.out.println("First result: " + firstResult);
+        System.out.println("Second result: " + secondResult);
+    }
+
+    public static List<Race> parseFirst(String input) {
+        String[] lines = input.split("\n");
+        String[] times = lines[0].substring(5).trim().split(" +");
+        String[] distance = lines[1].substring(9).trim().split(" +");
+        List<Race> races = IntStream.range(0, times.length)
+                .mapToObj(i -> new Race(Long.parseLong(times[i]), Long.parseLong(distance[i])))
+                .collect(Collectors.toList());
+        return races;
+    }
+
+    public static Race parseSecond(String input) {
+        String[] lines = input.split("\n");
+        long time = Long.parseLong(
+                Arrays.asList(lines[0].substring(5).trim().split(" +")).stream().collect(Collectors.joining("")));
+        long distance = Long.parseLong(Arrays.asList(lines[1].substring(9).trim().split(" +")).stream()
+                .collect(Collectors.joining("")));
+        return new Race(time, distance);
+    }
+
+    public static String getFirstPuzzleResult(String input) {
+        List<Race> races = parseFirst(input);
+        long result = races.stream().map(race -> {
+            var firstOptimal = 1 + Math
+                    .floor((-race.time + Math.sqrt(Math.pow(race.time, 2) - (-4) * (-race.bestMark))) / (-2));
+            var lastOptimal = (-1) + Math
+                    .ceil((-race.time - Math.sqrt(Math.pow(race.time, 2) - (-4) * (-race.bestMark))) / (-2));
+            return (long) (lastOptimal - firstOptimal + 1);
+        }).reduce(1l, (a, b) -> a * b);
+        return Long.toString(result);
+    }
+
+    public static String getSecondPuzzleResult(String input) {
+        Race race = parseSecond(input);
+        var firstOptimal = 1 + Math
+                .floor((-race.time + Math.sqrt(Math.pow(race.time, 2) - (-4) * (-race.bestMark))) / (-2));
+        var lastOptimal = (-1) + Math
+                .ceil((-race.time - Math.sqrt(Math.pow(race.time, 2) - (-4) * (-race.bestMark))) / (-2));
+        long result = (long) (lastOptimal - firstOptimal + 1);
+        return Long.toString(result);
+    }
+}
diff --git a/src/test/java/sugui/Day06Test.java b/src/test/java/sugui/Day06Test.java
new file mode 100644
index 0000000..bf7dd96
--- /dev/null
+++ b/src/test/java/sugui/Day06Test.java
@@ -0,0 +1,33 @@
+package sugui;
+
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+
+import org.junit.Test;
+
+/**
+ * Unit test for simple App.
+ */
+public class Day06Test {
+
+    public static String firstBasicInput = """
+            Time:      7  15   30
+            Distance:  9  40  200
+            """;
+    public static String secondBasicInput = firstBasicInput;
+    public static String firstBasicResult = "288";
+    public static String secondBasicResult = "71503";
+
+    @Test
+    public void firstBasicCase() throws IOException {
+        String actualResult = Day06.getFirstPuzzleResult(firstBasicInput);
+        assertEquals(firstBasicResult, actualResult);
+    }
+
+    @Test
+    public void secondBasicCase() throws IOException {
+        String actualResult = Day06.getSecondPuzzleResult(secondBasicInput);
+        assertEquals(secondBasicResult, actualResult);
+    }
+}