diff options
| -rw-r--r-- | 9.py | 52 |
1 files changed, 52 insertions, 0 deletions
@@ -0,0 +1,52 @@ +from dataclasses import dataclass + +@dataclass(frozen=True) +class Point: + x: int + y: int + def __add__(self, other): + return Point(self.x + other.x, self.y + other.y) + # def __mul__(self, other): + # return Point(self.x * other, self.y + other) + def __sub__(self, other): + return Point(self.x - other.x, self.y - other.y) + def norm(self): + return Point(min(max(self.x, -1), 1), min(max(self.y, -1), 1)) + +def pabs(p): + return max(abs(p.x), abs(p.y)) +delta = { + 'U': Point(0, 1), 'D': Point(0, -1), 'L': Point(-1, 0), 'R': Point(1, 0) +} +with open('9.in') as f: + inp = [tuple(line.rstrip().split()) for line in f] +inp = [(delta[d], int(q)) for d, q in inp] +def solve(tails): + knots = [Point(0, 0) for _ in range(tails + 1)] + visited = set() + visited.add(knots[-1]) + for move, count in inp: + for _ in range(count): + knots[0] += move + for i in range(1, len(knots)): + diff = knots[i-1] - knots[i] + if pabs(diff) > 1: + knots[i] += diff.norm() + visited.add(knots[-1]) + # for y in range(20, -20, -1): + # line = [] + # for x in range(-20, 20): + # p = Point(x, y) + # if p in visited: + # line.append('#') + # else: + # line.append(' ') + # try: + # line[-1] = str(knots.index(p)) + # except ValueError: + # pass + # print(''.join(line)) + return len(visited) + +print(solve(1)) +print(solve(9)) |