Day2.java

package com.sbaars.adventofcode.year17.days;

import com.sbaars.adventofcode.year17.Day2017;
import java.util.Arrays;
import java.util.stream.IntStream;

public class Day2 extends Day2017 {
  public Day2() {
    super(2);
  }

  public static void main(String[] args) {
    new Day2().printParts();
  }

  @Override
  public Object part1() {
    return dayStream()
        .map(line -> Arrays.stream(line.split("\t"))
            .mapToInt(Integer::parseInt)
            .summaryStatistics())
        .mapToInt(stats -> stats.getMax() - stats.getMin())
        .sum();
  }

  @Override
  public Object part2() {
    return dayStream()
        .map(line -> Arrays.stream(line.split("\t"))
            .mapToInt(Integer::parseInt)
            .toArray())
        .mapToInt(row -> IntStream.range(0, row.length)
            .flatMap(i -> IntStream.range(i + 1, row.length)
                .filter(j -> row[i] % row[j] == 0 || row[j] % row[i] == 0)
                .map(j -> row[i] % row[j] == 0 ? row[i] / row[j] : row[j] / row[i]))
            .findFirst()
            .orElse(0))
        .sum();
  }
}