Day 10 part 2 WIP

5 files changed, 183 insertions, 1 deletions

diff --git a/day10/day10.java b/day10/day10.java
index c25fffc..90bb74f 100644
--- a/day10/day10.java
+++ b/day10/day10.java
@@ -127,7 +127,151 @@ public class day10 {
   }
 
   public static String part2(RandomAccessFile input) throws IOException {
-    return "WIP";
+    int srow = -1, scol = -1;
+    ArrayList<ArrayList<Tile>> grid = new ArrayList<>();
+    String line;
+
+    while ((line = input.readLine()) != null) {
+      ArrayList<Tile> row = new ArrayList<>();
+      grid.add(row);
+      for (char ch: line.toCharArray()) {
+        switch (ch) {
+          case '|':
+            row.add(Tile.Vertical);
+            break;
+          case '-':
+            row.add(Tile.Horizontal);
+            break;
+          case 'L':
+            row.add(Tile.LBend);
+            break;
+          case 'J':
+            row.add(Tile.JBend);
+            break;
+          case '7':
+            row.add(Tile.SBend);
+            break;
+          case 'F':
+            row.add(Tile.FBend);
+            break;
+          case '.':
+            row.add(Tile.Ground);
+            break;
+          case 'S':
+            row.add(Tile.Start);
+            srow = grid.size() - 1;
+            scol = row.size() - 1;
+        }
+      }
+    }
+
+    boolean upcon = false, leftcon = false,
+            downcon = false, rightcon = false;
+
+    if (srow > 0) {
+      Tile t = grid.get(srow - 1).get(scol);
+      if (t == Tile.Vertical || t == Tile.SBend || t == Tile.FBend) {
+        upcon = true;
+      }
+    }
+
+    if (scol > 0) {
+      Tile t = grid.get(srow).get(scol - 1);
+      if (t == Tile.Horizontal || t == Tile.LBend || t == Tile.FBend) {
+        leftcon = true;
+      }
+    }
+
+    if (srow < (grid.size() - 1)) {
+      Tile t = grid.get(srow + 1).get(scol);
+      if (t == Tile.Vertical || t == Tile.LBend || t == Tile.JBend) {
+        downcon = true;
+      }
+    }
+
+    if (scol < (grid.get(0).size() - 1)) {
+      Tile t = grid.get(srow).get(scol + 1);
+      if (t == Tile.Horizontal || t == Tile.JBend || t == Tile.SBend) {
+        rightcon = true;
+      
+      }
+    }
+
+    Follower fa;
+    if (upcon && rightcon) {
+      grid.get(srow).set(scol, Tile.LBend);
+      fa = new Follower(grid, srow, scol, Dir.Up);
+    } else if (upcon && downcon) {
+      grid.get(srow).set(scol, Tile.Vertical);
+      fa = new Follower(grid, srow, scol, Dir.Up);
+    } else if (upcon && leftcon) {
+      grid.get(srow).set(scol, Tile.JBend);
+      fa = new Follower(grid, srow, scol, Dir.Up);
+    } else if (rightcon && downcon) {
+      grid.get(srow).set(scol, Tile.FBend);
+      fa = new Follower(grid, srow, scol, Dir.Right);
+    } else if (rightcon && leftcon) {
+      grid.get(srow).set(scol, Tile.Horizontal);
+      fa = new Follower(grid, srow, scol, Dir.Right);
+    } else if (downcon && leftcon) {
+      
+      grid.get(srow).set(scol, Tile.SBend);
+      fa = new Follower(grid, srow, scol, Dir.Down);
+    } else {
+      System.out.println("ERROR");
+      fa = null;
+    }
+
+    ArrayList<Integer[]> loop = new ArrayList<>();
+    loop.add(new Integer[]{srow, scol});
+    fa.step();
+    while (!(fa.row == srow && fa.col == scol)) {
+      loop.add(new Integer[]{fa.row, fa.col});
+      fa.step();
+    }
+
+    for (int r = 0; r < grid.size(); r++) {
+      for (int c = 0; c < grid.get(0).size(); c++) {
+        if (!isOnLoop(loop, new Integer[]{r, c})) {
+          grid.get(r).set(c, Tile.Ground);
+        }
+      }
+    }
+
+    int inloop = 0;
+    for (int r = 0; r < grid.size(); r++) {
+      for (int c = 0; c < grid.get(0).size(); c++) {
+        if (isInsideLoop(grid, r, c)) {
+          inloop += 1;
+        }
+      }
+    }
+
+    return "WIP";//Integer.toString(inloop);
+  }
+
+  static boolean isOnLoop(ArrayList<Integer[]> loop, Integer[] coord) {
+    for (Integer[] lc: loop) {
+      if (lc[0] == coord[0] && lc[1] == coord[1]) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  static boolean isInsideLoop(ArrayList<ArrayList<Tile>> grid, int row, int col) {
+    if (!(grid.get(row).get(col) == Tile.Ground)) {
+      return false;
+    }
+
+    int crossings = 0;
+    while (row >= 0) {
+      if (grid.get(row).get(col) == Tile.Horizontal) {
+        crossings += 1;
+      }
+      row -= 1;
+    }
+    return crossings % 2 == 1;
   }
 
   static enum Tile {
diff --git a/day10/test3 b/day10/test3
new file mode 100644
index 0000000..bd9cdf5
--- /dev/null
+++ b/day10/test3
@@ -0,0 +1,9 @@
+...........
+.S-------7.
+.|F-----7|.
+.||.....||.
+.||.....||.
+.|L-7.F-J|.
+.|..|.|..|.
+.L--J.L--J.
+...........
diff --git a/day10/test4 b/day10/test4
new file mode 100644
index 0000000..d6c0f21
--- /dev/null
+++ b/day10/test4
@@ -0,0 +1,9 @@
+..........
+.S------7.
+.|F----7|.
+.||....||.
+.||....||.
+.|L-7F-J|.
+.|..||..|.
+.L--JL--J.
+..........
diff --git a/day10/test5 b/day10/test5
new file mode 100644
index 0000000..adaae96
--- /dev/null
+++ b/day10/test5
@@ -0,0 +1,10 @@
+.F----7F7F7F7F-7....
+.|F--7||||||||FJ....
+.||.FJ||||||||L7....
+FJL7L7LJLJ||LJ.L-7..
+L--J.L7...LJS7F-7L7.
+....F-J..F7FJ|L7L7L7
+....L7.F7||L7|.L7L7|
+.....|FJLJ|FJ|F7|.LJ
+....FJL-7.||.||||...
+....L---J.LJ.LJLJ...
diff --git a/day10/test6 b/day10/test6
new file mode 100644
index 0000000..8f950ae
--- /dev/null
+++ b/day10/test6
@@ -0,0 +1,10 @@
+FF7FSF7F7F7F7F7F---7
+L|LJ||||||||||||F--J
+FL-7LJLJ||||||LJL-77
+F--JF--7||LJLJ7F7FJ-
+L---JF-JLJ.||-FJLJJ7
+|F|F-JF---7F7-L7L|7|
+|FFJF7L7F-JF7|JL---7
+7-L-JL7||F7|L7F-7F7|
+L.L7LFJ|||||FJL7||LJ
+L7JLJL-JLJLJL--JLJ.L