AOC3.java

package aoc;

import java.awt.Point;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class Day3 {

	static int part1(char[][] data, Point move, int width) {
		int cnt = 0;
		Point cur = new Point(0,0);
		while (cur.y < data.length) {
			if (data[cur.y][cur.x] == '#') {
				cnt++;
			}
			cur.translate(move.x,move.y);
			cur.x = cur.x % width;
		}
		return cnt;
	}

	public static void main(String[] args) throws IOException {
		
		char[][] records = Files.readAllLines(Paths.get("input3.txt"))
				.stream()
				.map(s -> s.toCharArray())
				.collect(Collectors.toList())
				.toArray(char[][]::new);
		
		int width = records[0].length;
		int res1 = part1(records, new Point(3,1), width);
		System.out.println(res1);
		
		long res2 = Stream
				.of(new Point(1,1), new Point(3,1), new Point(5,1),new Point(7,1),new Point(1,2))
				.mapToLong(slope -> part1(records, slope, width))
				.reduce((a,b) -> a*b)
				.getAsLong();
		
		System.out.println(res2);
	}

}