add timings

main.java.tmpl

@@ -1,12 +1,19 @@
 package src;
 
 import java.io.FileReader;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Scanner;
 
 public class Day00 {
     public static void main(String[] args) {
+        Instant start = Instant.now();
         part1();
+        Instant middle = Instant.now();
         part2();
+        Instant end = Instant.now();
+        IO.println("part 1: " + Duration.between(start, middle).toMillis() + " ms");
+        IO.println("part 2: " + Duration.between(middle, end).toMillis() + " ms");
     }
 
     private static void part1() {

src/Day01.java

@@ -1,12 +1,19 @@
 package src;
 
 import java.io.FileReader;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Scanner;
 
 public class Day01 {
     public static void main(String[] args) {
+        Instant start = Instant.now();
         part1();
+        Instant middle = Instant.now();
         part2();
+        Instant end = Instant.now();
+        IO.println("part 1: " + Duration.between(start, middle).toMillis() + " ms");
+        IO.println("part 2: " + Duration.between(middle, end).toMillis() + " ms");
     }
 
     private static void part1() {

src/Day02.java

@@ -1,12 +1,19 @@
 package src;
 
 import java.io.FileReader;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.Scanner;
 
 public class Day02 {
     public static void main(String[] args) {
+        Instant start = Instant.now();
         part1();
+        Instant middle = Instant.now();
         part2();
+        Instant end = Instant.now();
+        IO.println("part 1: " + Duration.between(start, middle).toMillis() + " ms");
+        IO.println("part 2: " + Duration.between(middle, end).toMillis() + " ms");
     }
 
     private static void part1() {

src/Day03.java

@@ -1,14 +1,21 @@
 package src;
 
 import java.io.FileReader;
+import java.time.Duration;
+import java.time.Instant;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Scanner;
 
 public class Day03 {
     public static void main(String[] args) {
+        Instant start = Instant.now();
         part1();
+        Instant middle = Instant.now();
         part2();
+        Instant end = Instant.now();
+        IO.println("part 1: " + Duration.between(start, middle).toMillis() + " ms");
+        IO.println("part 2: " + Duration.between(middle, end).toMillis() + " ms");
     }
 
     private static void part1() {
@@ -48,8 +55,7 @@ public class Day03 {
                 String raw = scanner.nextLine();
                 List<String> bank = List.of(raw.split(""));
                 // first, get the initial 12 batteries
-                List<String> curr = new ArrayList<>();
-                curr.addAll(bank.subList(0, 12));
+                List<String> curr = new ArrayList<>(bank.subList(0, 12));
                 for (int i = 12; i < bank.size(); i++) {
                     curr.add(bank.get(i)); // add the next battery to the end of the list
                     // find the smallest battery in the list that's ahead of a larger battery
@@ -61,8 +67,7 @@ public class Day03 {
                     }
                     curr.remove(t1);
                 }
-                String result = curr.stream().reduce("", String::concat);
-                sum += Long.parseLong(result);
+                sum += Long.parseLong(String.join("", curr));
             }
             IO.println(sum);
         } catch (Exception e) {