Complete day 1

src/main/java/com/mattrixwv/adventOfCode24/days/Problem2.java

@@ -0,0 +1,84 @@
+package com.mattrixwv.adventOfCode24.days;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Scanner;
+
+import com.mattrixwv.Stopwatch;
+
+public class Problem2 extends Problem{
+	private static final String inputFileName = "days/Problem1.txt";
+
+
+	public Problem2(){
+		super();
+		description = "Find the similarity score between the two columsn of numbers";
+		result = "Unresolved";
+	}
+
+
+	@Override
+	public String runSolution(){
+		Stopwatch timer = new Stopwatch();
+		timer.start();
+
+		int totalSimilarityScore = 0;
+
+		ArrayList<Integer> column1 = new ArrayList<>(1000);
+		ArrayList<Integer> column2 = new ArrayList<>(1000);
+
+
+		//Read elements from the file into memory
+		try(Scanner scanner = new Scanner(this.getClass().getClassLoader().getResourceAsStream(inputFileName))){
+			scanner.useDelimiter("\\s+");
+
+			while(scanner.hasNext()){
+				String token1 = scanner.next();
+				String token2 = scanner.next();
+
+				column1.add(Integer.parseInt(token1));
+				column2.add(Integer.parseInt(token2));
+			}
+		}
+
+		//Sort the two lists of ids
+		Collections.sort(column1);
+		Collections.sort(column2);
+
+		//Get the similarity score of each elements and keep a running sum
+		//The similarity score is the element in column 1 multiplied by the number of times it appears in column 2
+		for(Integer num : column1){
+			int count = count(num, column2);
+			totalSimilarityScore += (num * count);
+		}
+
+		//Save the results
+		timer.stop();
+		result = "The similarity score between the two columns of numbers is " + totalSimilarityScore + ".\nIt took " + timer.toString() + " to run the algorithm.";
+
+		return result;
+	}
+
+	//Get the number of times a number appears in the list
+	private int count(int num, List<Integer> list){
+		int cnt = 0;
+
+		for(Integer n : list){
+			if(n == num){
+				++cnt;
+			}
+			if(n > num){
+				break;
+			}
+		}
+
+		return cnt;
+	}
+}
+
+/*
+Find the similarity score between the two columns of numbers
+The similarity score between the two columns of numbers is 24316233.
+It took 17.875 milliseconds to run the algorithm.
+*/