Solve day 9 part 1

2022/day09_bridge.py

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+from __future__ import annotations
+
+import dataclasses
+
+
+def main(filename: str, expected_part_1: int = None, expected_part_2: int = None):
+    print(f"\n+ Running on {filename}")
+    with open(filename) as f:
+        data = f.read().strip().split("\n")
+
+    data = parse_data(data)
+    solution_part_1 = solve_part_1(data)
+
+    print(f"1. Found {solution_part_1}")
+    if expected_part_1:
+        assert expected_part_1 == solution_part_1
+
+    solution_part_2 = solve_part_2(data)
+    print(f"2. Found {solution_part_2}")
+    if expected_part_2:
+        assert expected_part_2 == solution_part_2
+
+
+Instruction = tuple[str, int]
+DataType = list[Instruction]
+
+
+@dataclasses.dataclass
+class Point:
+    x: int = 0
+    y: int = 0
+
+    def __eq__(self, other):
+        return (self.x, self.y) == (other.x, other.y)
+
+    def move(self, instruction: Instruction) -> None:
+        match instruction[0]:
+            case "R":
+                self.x += 1
+            case "L":
+                self.x -= 1
+            case "U":
+                self.y += 1
+            case "D":
+                self.y -= 1
+
+    def follow(self, other: Point) -> None:
+        if self == other:
+            return
+        if abs(self.x - other.x) <= 1 and abs(self.y - other.y) <= 1:
+            return
+        if other.x > self.x:
+            self.x += 1
+        elif other.x < self.x:
+            self.x -= 1
+        if other.y > self.y:
+            self.y += 1
+        elif other.y < self.y:
+            self.y -= 1
+
+    @property
+    def tuple(self) -> tuple[int, int]:
+        return self.x, self.y
+
+
+def parse_data(data: list[str]) -> DataType:
+    instructions = []
+    for line in data:
+        direction, count = line.split()
+        instructions.append((direction, int(count)))
+    return instructions
+
+
+def solve_part_1(instructions: DataType) -> int:
+    head = Point()
+    tail = Point()
+    visited = set()
+    for instruction in instructions:
+        count = instruction[1]
+        while count > 0:
+            head.move(instruction)
+            tail.follow(head)
+            tail_tuple = tail.tuple
+            visited.add(tail_tuple)
+            count -= 1
+    return len(visited)
+
+
+def solve_part_2(instructions: DataType) -> int:
+    return 0
+
+
+if __name__ == "__main__":
+    main("inputs/day09-test1", expected_part_1=13)
+    main("inputs/day09", expected_part_1=5619)

2022/inputs/day09-test1

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+R 4
+U 4
+L 3
+D 1
+R 4
+D 1
+L 5
+R 2