gistfile1.java

package test;

import java.io.File;
import java.io.FileNotFoundException;
import java.util.LinkedList;
import java.util.Scanner;

public class PathSum {

	public static void main(String[] args) throws Exception {
		LinkedList<int[]> tiles = loadTiles(new File("tiles.txt"));
		System.out.println(calculatePathSum(tiles));
	}

	private static LinkedList<int[]> loadTiles(File tilesFile)
			throws FileNotFoundException {
		LinkedList<int[]> tiles = new LinkedList<int[]>();
		Scanner in = new Scanner(tilesFile);
		while (in.hasNextLine()) {
			String[] numberStrings = in.nextLine().split(" ");
			int[] numbers = new int[numberStrings.length];
			for (int i = 0; i < numberStrings.length; i++) {
				numbers[i] = Integer.parseInt(numberStrings[i]);
			}
			tiles.addFirst(numbers);
		}
		in.close();
		return tiles;
	}

	private static int calculatePathSum(LinkedList<int[]> tiles) {
		while (tiles.size() > 1) {
			int[] currentRow = tiles.poll();
			int[] parentRow = tiles.poll();
			for (int i = 0; i < currentRow.length - 1; i++) {
				int max = Math.max(currentRow[i], currentRow[i + 1]);
				parentRow[i] += max;
			}
			tiles.addFirst(parentRow);
		}
		return tiles.poll()[0];
	}

}