2023 dec 16th

Python/2023/16/main.py

@@ -0,0 +1,72 @@
+# y, x
+# j, i
+
+input = open("input", 'r')#.read().rstrip()
+
+data = []
+
+for line in input:
+    data.append(list(line.rstrip()))
+
+
+def printenergized(pos, energized):
+    for j, row in enumerate(data):
+        for i, char in enumerate(row):
+            if pos == (j,i):
+                print("*", end="")
+            elif (j, i) in energized:
+                print("#", end="")
+            else:
+                print(char, end="")
+        print()
+    print()
+
+def beam(split_stack):
+    assert(len(data) == len(data[0]))
+    energized = set()
+    prevpos = set()
+    while len(split_stack) > 0:
+        pos, dr = split_stack.pop()
+        while min(pos) >= 0 and max(pos) < len(data):
+            energized.add(pos)
+            if pos+dr in prevpos:
+                break
+            else:
+                prevpos.add(pos+dr)
+            # printenergized(pos, energized)
+            curr_space = data[pos[0]][pos[1]]
+            if curr_space == "/":
+                dr = (-dr[1], -dr[0])
+            elif curr_space == "\\":
+                dr = (dr[1], dr[0])
+            elif curr_space == "-" and dr[0] != 0:
+                split_stack.append(((pos[0], pos[1]+1),(0, 1)))
+                split_stack.append(((pos[0], pos[1]-1),(0,-1)))
+                break
+            elif curr_space == "|" and dr[1] != 0:
+                split_stack.append(((pos[0]+1, pos[1]),( 1,0)))
+                split_stack.append(((pos[0]-1, pos[1]),(-1,0)))
+                break
+            pos = tuple(sum(elems) for elems in zip(pos,dr))
+    return energized
+
+split_stack = [((0,0),(0,1))]
+energized = beam(split_stack)
+print(len(energized))
+
+energizes = []
+
+# Left & Right
+for dr, x in zip([1, -1], [0, len(data[0])-1]):
+    for j in range(len(data)):
+        split_stack = [((j,x),(0,dr))]
+        energizes.append(len(beam(split_stack)))
+
+# Top & Bottom
+for dr, y in zip([1, -1], [0, len(data)-1]):
+    assert(len(data[-1]) == len(data[0]))
+    for i in range(len(data[0])):
+        split_stack = [((y,i),(dr,0))]
+        energizes.append(len(beam(split_stack)))
+
+print(max(energizes))