Add 2022 solutions

2022/d9.py

@@ -0,0 +1,128 @@
+EXAMPLE = """
+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2
+"""
+
+def clean(text: str) -> list[str]:
+    return list(filter(lambda l: l.strip() != "", text.splitlines()))
+
+def new_pos(h_pos, t_pos, dir):
+    if dir == "R":
+        new_h_pos = (h_pos[0] + 1, h_pos[1])
+    elif dir == "U":
+        new_h_pos = (h_pos[0], h_pos[1] + 1)
+    elif dir == "L":
+        new_h_pos = (h_pos[0] - 1, h_pos[1])
+    elif dir == "D":
+        new_h_pos = (h_pos[0], h_pos[1] - 1)
+    elif dir == "NONE":
+        new_h_pos = (h_pos[0], h_pos[1])
+    else:
+        raise Exception("Unexpected direction.")
+
+    #  xxxxx
+    #  x---x     
+    #  x-O-x          
+    #  x---x   
+    #  xxxxx
+    dx, dy = t_pos[0] - new_h_pos[0], t_pos[1] - new_h_pos[1]
+    delta = {
+        (-1, -1): (0, 0),
+        (-1, 0): (0, 0),
+        (-1, 1): (0, 0),
+        (0, -1): (0, 0),
+        (0, 0): (0, 0),
+        (0, 1): (0, 0),
+        (1, -1): (0, 0),
+        (1, 0): (0, 0),
+        (1, 1): (0, 0),
+        (-2, 2): (1, -1),
+        (-2, 1): (1, -1),
+        (-2, 0): (1, 0),
+        (-2, -1): (1, 1),
+        (-2, -2): (1, 1),
+        (2, 2): (-1, -1),
+        (2, 1): (-1, -1),
+        (2, 0): (-1, 0),
+        (2, -1): (-1, 1),
+        (2, -2): (-1, 1),
+        (-1, 2): (1, -1),
+        (-1, -2): (1, 1),
+        (0, 2): (0, -1),
+        (0, -2): (0, 1),
+        (1, 2): (-1, -1),
+        (1, -2): (-1, 1),
+    }
+    dx_, dy_ = delta[(dx, dy)]
+    new_t_pos = t_pos[0] + dx_, t_pos[1] + dy_
+    # print(f"{h_pos=} {t_pos=} {dir=}")
+    # print(f"{new_h_pos=} {dx=} {dy=}")
+    # print(f"{new_t_pos=}")
+    # print("----")
+    return new_t_pos, new_h_pos
+
+def solve(lines: list[str]):
+    pos = set()
+    h_pos = (0, 0)
+    t_pos = (0, 0)
+    pos.add(t_pos)
+    for i in range(len(lines)):
+        dir, amount = lines[i].split()
+        for _ in range(int(amount)):
+            t_pos, h_pos = new_pos(h_pos, t_pos, dir)
+            pos.add(t_pos)
+    # 44:00
+    return len(pos)
+
+EXAMPLE2 = """
+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20
+"""
+
+def solve2(lines: list[str]):
+    vis = set()
+    poss = [(0, 0) for _ in range(10)]
+    vis.add((0, 0))
+    for i in range(len(lines)):
+        dir, amount = lines[i].split()
+        for _ in range(int(amount)):
+            for i in range(len(poss) - 1):
+                h_pos = poss[i]
+                t_pos = poss[i + 1]
+                if i == 0:
+                    t_pos, h_pos = new_pos(h_pos, t_pos, dir)
+                else:
+                    t_pos, h_pos = new_pos(h_pos, t_pos, "NONE")
+                poss[i] = h_pos
+                poss[i + 1] = t_pos
+            vis.add(poss[-1])
+    # 58:00
+    return len(vis)
+
+def main():
+    example = clean(EXAMPLE)
+    print("Example  1:", solve(example))
+
+    data = clean(open("d9.txt").read())
+    print("Solution 1:", solve(data))
+
+    example = clean(EXAMPLE2)
+    print("Example  2:", solve2(example))
+
+    data = clean(open("d9.txt").read())
+    print("Solution 2:", solve2(data))
+
+if __name__ == "__main__":
+    main()