day 16 py

src/python/16_rk.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+import sys
+import collections
+
+def parse():
+    l = []
+    with open(sys.argv[1], 'r') as infile:
+        for line in infile:
+            l.append(line.strip())
+    return l
+
+def sol1(l):
+    togo = collections.deque([((0, 0), (0, 1))])
+    return sol(l, togo)
+
+def sol2(l):
+    width = len(l[0])
+    height = len(l)
+
+    s = 0
+
+    # edges
+    for i in range(0, width):
+        cmd = ((0, i), (1, 0))
+        s = max(s, sol(l, collections.deque([cmd])))
+        cmd = ((height-1, i), (-1, 0))
+        s = max(s, sol(l, collections.deque([cmd])))
+        pass
+    for i in range(0, height):
+        cmd = ((i, 0), (0, 1))
+        s = max(s, sol(l, collections.deque([cmd])))
+        cmd = ((i, width-1), (0, -1))
+        s = max(s, sol(l, collections.deque([cmd])))
+        pass
+
+    # list of tuple of set
+    #  l_corner = []
+    #  for pos in [
+            #  (0, 0),
+            #  (0, width-1),
+            #  (height-1, 0),
+            #  (height-1, width-1),
+            #  ]:
+        #  s1 = sol(l, collections.deque([(pos, (0, 1 if pos[1] == 0 else -1))]))
+        #  s2 = sol(l, collections.deque([(pos, (1 if pos[0] == 0 else -1, 0))]))
+        #  l_corner.append([s1, s2])
+
+    #  s = 0
+    #  for i in range(16):
+        #  v = visited
+        #  v = v.union(l_corner[0][(i) & 1])
+        #  v = v.union(l_corner[1][(i >> 1) & 1])
+        #  v = v.union(l_corner[2][(i >> 2) & 1])
+        #  v = v.union(l_corner[3][(i >> 3) & 1])
+        #  s = max(s, len(v))
+    return s
+
+
+def sol(l, togo):
+    visited = set()
+    width = len(l[0])
+    height = len(l)
+    while len(togo):
+        # position and direction
+        pos, di = togo.pop()
+        if pos[0] < 0 or pos[0] >= height or pos[1] < 0 or pos[1] >= width:
+            continue
+        if (pos, di) in visited:
+            continue
+        visited.add((pos, di))
+
+        sign = l[pos[0]][pos[1]]
+
+        if sign == "." or (sign == "-" and di[0] == 0) or (sign == "|" and di[1] == 0):
+            # go in the same direction
+            togo.append(((pos[0] + di[0], pos[1] + di[1]), di))
+        elif sign == "-":
+            # go in two horizontal direction (y)
+            togo.append(((pos[0], pos[1] + 1), (0,  1)))
+            togo.append(((pos[0], pos[1] - 1), (0, -1)))
+        elif sign == "|":
+            # go in two horizontal direction (y)
+            togo.append(((pos[0] + 1, pos[1]), (1,  0)))
+            togo.append(((pos[0] - 1, pos[1]), (-1, 0)))
+        elif sign == "/":
+            # go in two horizontal direction (y)
+            togo.append(((pos[0] - di[1], pos[1] - di[0]), (-di[1],  -di[0])))
+        elif sign == "\\":
+            # go in two horizontal direction (y)
+            togo.append(((pos[0] + di[1], pos[1] + di[0]), (di[1],  di[0])))
+            pass
+        pass
+    return len(set([pos for pos, _ in visited]))
+
+def main():
+    l = parse()
+    print(sol1(l))
+    print(sol2(l))
+    pass
+
+main()