Create Day14.java

Author: nsiwnf

Day14.java

@@ -0,0 +1,138 @@
+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));
+  }
+}