Day 22 part 1.

d22.py

@@ -0,0 +1,69 @@
+from lib import *
+
+EXAMPLE = """        ...#
+        .#..
+        #...
+        ....
+...#.......#
+........#...
+..#....#....
+..........#.
+        ...#....
+        .....#..
+        .#......
+        ......#.
+
+10R5L5R10L4R5L5"""
+
+
+DIRS = [
+    (0, 1),
+    (1, 0),
+    (0, -1),
+    (-1, 0),
+]
+
+
+def solve(input: Input, second=False):
+    grid, steps = input.text.split("\n\n")
+    grid = list(map(list, grid.splitlines()))
+    rows = len(grid)
+
+    startcol = 0
+    while grid[0][startcol] == ' ':
+        startcol += 1
+    pos = (0, startcol)
+    dir = (0, 1)
+    insts = re.compile(r"(\d+)([LR])").findall(steps)
+    lastn = re.compile(r"\d+").findall(steps)[-1]
+    insts.append((lastn, None))
+    for n, turn in insts:
+        nrow, ncol = pos
+        for _ in range(int(n)):
+            nrow = (nrow + dir[0]) % rows
+            ncol = (ncol + dir[1]) % len(grid[nrow])
+            while grid[nrow][ncol] == ' ':
+                nrow = (nrow + dir[0]) % rows
+                ncol = (ncol + dir[1]) % len(grid[nrow])
+            if grid[nrow][ncol] == '#':
+                break
+            pos = (nrow, ncol)
+        if turn is not None:
+            dir = DIRS[(DIRS.index(dir) + 1 if turn == 'R' else DIRS.index(dir) - 1) % 4]
+
+    return 1000 * (pos[0] + 1) + 4 * (pos[1] + 1) + DIRS.index(dir)
+
+def main():
+    DAY_INPUT = "i22.txt"
+
+    print("Example  1:", solve(Input(EXAMPLE)))
+    print("Solution 1:", solve(Input(DAY_INPUT)))
+
+    # print("Example  2:", solve(Input(EXAMPLE), True))
+    return
+
+    print("Solution 2:", solve(Input(DAY_INPUT), True))
+    return
+
+if __name__ == "__main__":
+    main()