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Day14.java
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Day14.java
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package com.adventofcode.advent2017;
import java.util.Arrays;
import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;
public class Day14 {
static int part1(String input) {
int[] stringOrig = new int[256];
for (int i = 0; i < 256; i++) {
stringOrig[i] = i;
}
int[] string = Arrays.copyOf(stringOrig, 256);
byte[][] grid = new byte[128][128];
int count = 0;
for (int i = 0; i < 128; i++) {
count += part1((input + '-' + i).getBytes(), string, grid[i]);
System.arraycopy(stringOrig, 0, string, 0, 256);
}
// return count; // Part 1
return part2(grid);
}
static class Point {
int x;
int y;
public Point(int x, int y) {
this.x = x;
this.y = y;
}
}
static int part2(byte[][] grid) {
Queue<Point> pointQueue = new ArrayBlockingQueue<>(1000);
int regions = 0;
while (addNextPoint(grid, pointQueue)) {
regions++;
while (!pointQueue.isEmpty()) {
Point p = pointQueue.poll();
int x = p.x;
int y = p.y;
// mark visited
if (grid[x][y] == 1) {
grid[x][y] = 2;
if (x < 127 && grid[x + 1][y] == 1) {
pointQueue.add(new Point(x + 1, y));
}
if (x > 0 && grid[x - 1][y] == 1) {
pointQueue.add(new Point(x - 1, y));
}
if (y < 127 && grid[x][y + 1] == 1) {
pointQueue.add(new Point(x, y + 1));
}
if (y > 0 && grid[x][y - 1] == 1) {
pointQueue.add(new Point(x, y - 1));
}
}
}
}
return regions;
}
private static boolean addNextPoint(byte[][] grid, Queue<Point> pointQueue) {
for (int x = 0; x < 128; x++) {
for (int y = 0; y < 128; y++) {
if (grid[x][y] == 1) {
pointQueue.add(new Point(x, y));
return true;
}
}
}
return false;
}
static int part1(byte[] input1, int[] string, byte[] row) {
byte[] input = new byte[input1.length + 5];
byte[] suffix = {17, 31, 73, 47, 23};
System.arraycopy(input1, 0, input, 0, input1.length);
System.arraycopy(suffix, 0, input, input1.length, suffix.length);
int index = 0;
int skipSize = 0;
for (int r = 0; r < 64; r++) {
for (int length : input) {
for (int i = 0; i < length / 2; i++) {
int n = (i + index) % string.length;
int m = (length - i - 1 + index) % string.length;
int b = string[m];
string[m] = string[n];
string[n] = b;
}
index = (index + length + skipSize) % string.length;
skipSize++;
}
}
int count = 0;
byte[] hashes = new byte[16];
for (int hashidx = 0; hashidx < 16; hashidx++) {
for (int i = 0; i < 16; i++) {
int a = string[16 * hashidx + i];
hashes[hashidx] ^= a;
}
for (int i = 0; i < 8; i++) {
row[8 * hashidx + 7 - i] = (byte) ((hashes[hashidx] >> i) & 1);
count += row[8 * hashidx + 7 - i];
}
}
return count;
}
public static void main(String[] args) {
String input = "ffayrhll";
// input = "flqrgnkx";
System.out.println(part1(input));
}
}