day 9

py-ver/09.py

@@ -0,0 +1,129 @@
+import os
+debug_draw = False
+
+with open("09.txt") as f:
+  data = f.read()
+ex_data = """R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2"""
+ex2_data = """R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20"""
+
+def is_adj(a, b):
+  return abs(a[0] - b[0]) <= 1 and abs(a[1] - b[1]) <= 1
+
+dirs = {"NIL": (0, 0), "R": (1, 0), "U": (0, 1), "L": (-1, 0), "D": (0, -1),
+        "UR": (1, 1), "UL": (-1, 1), "DR": (1, -1), "DL": (-1, -1)}
+dir_inv = dict()
+for k, v in dirs.items():
+  dir_inv[v] = k
+
+def move(dir, head, tail):
+
+  dx, dy = dirs[dir]
+  hx, hy = head
+  tx, ty = tail
+  nhx, nhy = hx + dx, hy + dy
+
+  if is_adj((nhx, nhy), (tx, ty)): ntx, nty = tx, ty
+  elif nhx != tx and nhy != ty:
+    # import pdb; pdb.set_trace()
+    # Move diagonally
+    ax, ay = nhx - tx, nhy - ty
+    if ax != 0 and ay != 0:
+      ax, ay = abs(ax) // ax, abs(ay) // ay
+      ntx, nty = tx + ax, ty + ay
+  elif nhx == tx:
+    if dir == "L" or dir == "R": ntx, nty = tx, ty
+    elif abs(nhy - ty) == 2: ntx, nty = tx, ty + dy
+    else: ntx, nty = tx, ty
+  elif nhy == ty:
+    if dir == "U" or dir == "D": ntx, nty = tx, ty
+    elif abs(nhx - tx) == 2: ntx, nty = tx + dx, ty
+    else: ntx, nty = tx, ty
+  else: ntx, nty = hx, hy
+
+  return (nhx, nhy), (ntx, nty)
+
+def solve1(data):
+  head = (0, 0)
+  tail = (0, 0)
+  
+  all_pos = set()
+  all_pos.add(tail)
+
+  for line in data.splitlines():
+    line = line.strip()
+    dir, dist = line.split(" ")
+    dist = int(dist)
+    for _ in range(dist):
+      head, tail = move(dir, head, tail)
+      all_pos.add(tail)
+
+  print(len(all_pos))
+
+def move_multiple(dir, segs):
+  new_segs = []
+  cur_dir = dir
+  for i in range(1, len(segs)):
+    head, tail = segs[i - 1], segs[i]
+    nhead, ntail = move(cur_dir, head, tail)
+    new_segs.append(nhead)
+    cur_dir = dir_inv[(ntail[0] - tail[0], ntail[1] - tail[1])]
+  new_segs.append(ntail)
+  return new_segs
+
+def solve2(data):
+  segs = []
+  for _ in range(10): segs.append((0, 0))
+
+  all_pos = set()
+  all_pos.add((0, 0))
+
+  for line in data.splitlines():
+    line = line.strip()
+    dir, dist = line.split(" ")
+    dist = int(dist)
+    for times in range(dist):
+      if debug_draw: os.system("clear")
+      segs = move_multiple(dir, segs)
+      all_pos.add(segs[-1])
+
+      if debug_draw:
+        print(dir, dist - times - 1)
+        segs_draw = dict()
+        for i, seg in enumerate(segs):
+          segs_draw[seg] = i
+        print(segs)
+        print(segs_draw)
+        for y in range(20, -20, -1):
+          for x in range(-20, 20):
+            n = segs_draw.get((x, y))
+            if n is None: print(".", end="")
+            else: print(n, end="")
+          print()
+        input()
+
+  print(len(all_pos))
+
+head = (1, 1)
+tail = (0, 0)
+# print(move("UL", head, tail))
+
+solve1(ex_data)
+solve1(data)
+
+solve2(ex_data)
+solve2(ex2_data)
+solve2(data)