Create Day19.java

Author: nsiwnf

Day19.java

@@ -0,0 +1,109 @@
+
+import java.util.Arrays;
+import java.util.List;
+
+public class Day19 {
+
+  static class Point {
+    int x;
+
+    int y;
+
+    char direction; // D, U, L, R
+
+    String result;
+
+    public Point(int x, int y, char direction, String result) {
+      this.x = x;
+      this.y = y;
+      this.result = result;
+      this.direction = direction;
+    }
+  }
+
+  static int part1(List<String> rows) {
+    char[][] grid = new char[rows.size()][rows.iterator().next().length()];
+    for (int i = 0; i < rows.size(); i++) {
+      String row = rows.get(i);
+      if (row.length() < rows.size()) {
+        grid[i] = new char[rows.size()];
+        Arrays.fill(grid[i], ' ');
+        System.arraycopy(row.toCharArray(), 0, grid[i], 0, row.length());
+      }
+      else {
+        grid[i] = row.toCharArray();
+      }
+    }
+
+    Point p = null;
+    for (int i = 0; i < grid[0].length; i++) {
+      if (grid[0][i] == '|') {
+        p = new Point(0, i, 'D', "");
+        break;
+      }
+    }
+
+    int steps = 0;
+    while (p != null) {
+      if (p.result.length() == 10) {
+        System.out.println(p.result);
+//         return p.result;
+        return steps;
+      }
+
+      steps++;
+
+      if (grid[p.x][p.y] >= 'A' && grid[p.x][p.y] <= 'Z') {
+        p.result += grid[p.x][p.y];
+      }
+
+      if (grid[p.x][p.y] == '+') {
+        // change direction
+        if (p.direction == 'D' || p.direction == 'U') {
+          if (p.y > 0 && grid[p.x][p.y - 1] == '-') {
+            p.y--;
+            p.direction = 'L';
+          }
+          else if (p.y < grid[p.x].length - 1 && grid[p.x][p.y + 1] == '-') {
+            p.y++;
+            p.direction = 'R';
+          }
+        }
+        else if (p.direction == 'L' || p.direction == 'R') {
+          if (p.x > 0 && grid[p.x - 1][p.y] == '|') {
+            p.x--;
+            p.direction = 'U';
+          }
+          else if (p.x < grid.length - 1 && grid[p.x + 1][p.y] == '|') {
+            p.x++;
+            p.direction = 'D';
+          }
+        }
+      }
+      // keep going
+      else if (p.direction == 'D') {
+        p.x++;
+      }
+      else if (p.direction == 'U') {
+        p.x--;
+      }
+      else if (p.direction == 'L') {
+        p.y--;
+      }
+      else if (p.direction == 'R') {
+        p.y++;
+      }
+      else {
+        p = null;
+      }
+    }
+
+    return -1;
+  }
+
+  public static void main(String[] args) {
+    List<String> input = Util.readInput("day19.input");
+
+    System.out.println(part1(input)); // 17302
+  }
+}