Advent of Code 2021 - Day 6

Author: CodingNagger

pom.xml

@@ -20,9 +20,9 @@
 
   <dependencies>
     <dependency>
-      <groupId>junit</groupId>
-      <artifactId>junit</artifactId>
-      <version>4.11</version>
+      <groupId>org.junit.jupiter</groupId>
+      <artifactId>junit-jupiter</artifactId>
+      <version>5.8.2</version>
       <scope>test</scope>
     </dependency>
     <dependency>

src/main/java/com/codingnagger/App.java

@@ -13,9 +13,9 @@ public class App {
     public static void main(String[] args) throws IOException {
         System.out.println("Advent of Code 2021");
 
-        List<String> input = InputLoader.Load("day5.txt");
+        List<String> input = InputLoader.Load("day6.txt");
 
-        Day day = new Day5();
+        Day day = new Day6();
 
         System.out.println("Part 1:");
         System.out.println(day.partOne(input));

src/main/java/com/codingnagger/days/Day6.java

@@ -0,0 +1,72 @@
+package com.codingnagger.days;
+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import static com.codingnagger.utils.InputConverter.convertToIntegers;
+
+public class Day6 implements Day {
+    @Override
+    public String partOne(List<String> input) {
+        LanterfishPool pool = parse(input);
+        pool.run(80);
+        return pool.fishCount().toString();
+    }
+
+    @Override
+    public String partTwo(List<String> input) {
+        LanterfishPool pool = parse(input);
+        pool.run(256);
+        return pool.fishCount().toString();
+    }
+
+    public LanterfishPool parse(List<String> input) {
+        return new LanterfishPool(convertToIntegers(input.get(0), ","));
+    }
+
+    public static class LanterfishPool {
+        private final BigInteger[] fishes;
+
+        public LanterfishPool(List<Integer> fishStates) {
+            fishes = new BigInteger[9];
+
+            for (int i = 0; i < 9; i++) {
+                fishes[i] = BigInteger.ZERO;
+            }
+
+            for (Integer state : fishStates) {
+                fishes[state] = fishes[state].add(BigInteger.ONE);
+            }
+        }
+
+        public void run(int cycleCount) {
+            for (int i = 0; i < cycleCount; i++) {
+                tick();
+            }
+        }
+
+        public void tick() {
+            BigInteger newBorns = fishes[0];
+
+            System.arraycopy(fishes, 1, fishes, 0, 8);
+
+            fishes[6] = fishes[6].add(newBorns);
+            fishes[8] = newBorns;
+        }
+
+        public BigInteger fishCount() {
+            BigInteger count = BigInteger.ZERO;
+
+            for (int i = 0; i < 9; i++) {
+                count = count.add(fishes[i]);
+            }
+
+            return count;
+        }
+    }
+}

src/main/java/com/codingnagger/utils/InputConverter.java

@@ -1,10 +1,15 @@
 package com.codingnagger.utils;
 
+import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 
 public class InputConverter {
     public static List<Integer> convertToIntegers(List<String> input) {
         return input.stream().map(Integer::parseInt).collect(Collectors.toList());
     }
+
+    public static List<Integer> convertToIntegers(String input, String separator) {
+        return Arrays.stream(input.split(",")).map(Integer::parseInt).collect(Collectors.toList());
+    }
 }

src/main/resources/day6.txt

@@ -0,0 +1 @@
+1,1,3,1,3,2,1,3,1,1,3,1,1,2,1,3,1,1,3,5,1,1,1,3,1,2,1,1,1,1,4,4,1,2,1,2,1,1,1,5,3,2,1,5,2,5,3,3,2,2,5,4,1,1,4,4,1,1,1,1,1,1,5,1,2,4,3,2,2,2,2,1,4,1,1,5,1,3,4,4,1,1,3,3,5,5,3,1,3,3,3,1,4,2,2,1,3,4,1,4,3,3,2,3,1,1,1,5,3,1,4,2,2,3,1,3,1,2,3,3,1,4,2,2,4,1,3,1,1,1,1,1,2,1,3,3,1,2,1,1,3,4,1,1,1,1,5,1,1,5,1,1,1,4,1,5,3,1,1,3,2,1,1,3,1,1,1,5,4,3,3,5,1,3,4,3,3,1,4,4,1,2,1,1,2,1,1,1,2,1,1,1,1,1,5,1,1,2,1,5,2,1,1,2,3,2,3,1,3,1,1,1,5,1,1,2,1,1,1,1,3,4,5,3,1,4,1,1,4,1,4,1,1,1,4,5,1,1,1,4,1,3,2,2,1,1,2,3,1,4,3,5,1,5,1,1,4,5,5,1,1,3,3,1,1,1,1,5,5,3,3,2,4,1,1,1,1,1,5,1,1,2,5,5,4,2,4,4,1,1,3,3,1,5,1,1,1,1,1,1

src/test/java/com/codingnagger/AppTest.java

@@ -1,8 +1,7 @@
 package com.codingnagger.days;
 
 import com.codingnagger.utils.InputLoader;
-import org.junit.Test;
-
+import org.junit.jupiter.api.Test;
 
 import java.util.List;
 

src/test/java/com/codingnagger/days/Day1Test.java

@@ -1,9 +1,8 @@
 package com.codingnagger.days;
 
 import com.codingnagger.utils.InputLoader;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-import java.io.IOException;
 import java.util.List;
 
 import static org.assertj.core.api.Assertions.assertThat;

src/test/java/com/codingnagger/days/Day2Test.java

@@ -1,7 +1,7 @@
 package com.codingnagger.days;
 
 import com.codingnagger.utils.InputLoader;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.util.List;
 

src/test/java/com/codingnagger/days/Day3Test.java

@@ -1,7 +1,7 @@
 package com.codingnagger.days;
 
 import com.codingnagger.utils.InputLoader;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.util.List;
 

src/test/java/com/codingnagger/days/Day4Test.java

@@ -1,7 +1,7 @@
 package com.codingnagger.days;
 
 import com.codingnagger.utils.InputLoader;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 import java.util.List;
 

src/test/java/com/codingnagger/days/Day5Test.java

@@ -0,0 +1,41 @@
+package com.codingnagger.days;
+
+import com.codingnagger.utils.InputLoader;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import java.math.BigInteger;
+import java.util.Arrays;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class Day6Test {
+    private static final List<String> INPUT = InputLoader.LoadTest("day6.txt");
+    private static final Day DAY = new Day6();
+
+    @Test
+    public void partOne_shouldReturnExpectedResult() {
+        String result = DAY.partOne(INPUT);
+
+        assertThat(result).isEqualTo("5934");
+    }
+
+    @ParameterizedTest
+    @CsvSource({"5,10", "6,10","7,10","8,10","10,12", "18,26"})
+    public void partOne_lanternFishCount(int cyclesCount, BigInteger expectedResult) {
+        Day6.LanterfishPool pool = new Day6.LanterfishPool(Arrays.asList(3,4,3,1,2));
+
+        pool.run(cyclesCount);
+
+        assertThat(pool.fishCount()).isEqualTo(expectedResult);
+    }
+
+    @Test
+    public void partTwo_shouldReturnExpectedResult() {
+        String result = DAY.partTwo(INPUT);
+
+        assertThat(result).isEqualTo("26984457539");
+    }
+}

src/test/java/com/codingnagger/days/Day6Test.java

@@ -0,0 +1 @@
+3,4,3,1,2