aoc

day15b.cpp (3835B)

---

 /*
 The code here is not great, but I don't feel like cleaning it up
 */
 
 #include <iostream>
 #include <cstdint>
 #include <algorithm>
 #include <string>
 #include <string_view>
 #include <vector>
 #include <set>
 using namespace std;
 
 class Direction {
 public:
 	const int U, R;
 
 	Direction(char c) :
 	    U{c == 'v' ? 1 : (c == '^' ? -1 : 0)},
 	    R{c == '>' ? 1 : (c == '<' ? -1 : 0)} {}
 
 	Direction(const int i, const int j) : U{i}, R{j} {}
 
 	Direction turnright() const {
 		return turn(-1, 0);
 	}
 
 	Direction turnleft() const {
 		return turn(1, 0);
 	}
 
 	bool operator<(const Direction& d) const { // For set<Direction>
 		return this->U < d.U || (this->U == d.U && this->R < d.R);
 	}
 private:
 	Direction turn(int64_t sin, int64_t cos) const {
 		return Direction(cos * U - sin * R, sin * U + cos * R);
 	}
 };
 
 class Position {
 public:
 	int64_t i, j;
 
 	Position() : Position(0, 0) {}
 
 	Position(int64_t a, int64_t b) : i{a}, j{b} {}
 
 	Position step(const Direction d) const {
 		return Position(i+d.U, j+d.R);
 	}
 };
 
 const Direction all_directions[] = {
 	Direction(1, 0), Direction(-1, 0), Direction(0, 1), Direction(0, -1)
 };
 
 class Board {
 public:
 	int64_t N, M;
 	Position robot;
 
 	Board(const vector<string>& lines) :
 	    N{static_cast<int64_t>(lines.size())},
 	    M{static_cast<int64_t>(lines[0].size())},
 	    cells(M*N)
 	{
 		for (int64_t i = 0; i < N; i++) {
 			for (int64_t j = 0; j < M; j++) {
 				cells[M*i+j] = lines[i][j];
 				if (lines[i][j] == '@')
 					robot = Position(i, j);
 			}
 		}
 	}
 
 	char& operator[](const Position p) {
 		if (const auto c = coord(p); c == -1)
 			return out_of_bound;
 		else
 			return cells[c];
 	}
 
 	void move_robot(const Direction d) {
 		if (move(robot, d))
 			robot = robot.step(d);
 	}
 
 	int64_t gps() {
 		int64_t tot = 0;
 		for (Position p(0, 0); p.i < N; p.i++)
 			for (p.j = 0; p.j < M; p.j++)
 				if ((*this)[p] == '[')
 					tot += 100*p.i + p.j;
 		return tot;
 	}
 
 	void print() {
 		for (Position p(0, 0); p.i < N; p.i++) {
 			for (p.j = 0; p.j < M; p.j++)
 				cout << (*this)[p];
 			cout << endl;
 		}
 	}
 private:
 	char out_of_bound = '$';
 
 	vector<char> cells;
 
 	int64_t coord(const Position p) const {
 		auto [i, j] = p;
 		return i >= N || i < 0 || j >= M || j < 0 ? -1 : M * i + j;
 	}
 
 	bool move(Position p, Direction d) {
 		return d.U == 0 ? move_h(p, d) : move_v(p, d);
 	}
 
 	bool move_h(Position p, Direction d) {
 		auto q = p.step(d);
 		switch ((*this)[q]) {
 		case '.':
 			(*this)[q] = (*this)[p];
 			(*this)[p] = '.';
 			return true;
 		case '[':
 		case ']':
 			return move(q, d) ? move(p, d) : false;
 		default:
 			return false;
 		}
 	}
 
 	bool move_v(Position p, Direction d) {
 		if (!isfree_v(p, d))
 			return false;
 
 		auto q = p.step(d);
 		if ((*this)[q] == '[') {
 			move_v(q, d);
 			move_v(q.step(Direction('>')), d);
 		}
 		if ((*this)[q] == ']') {
 			move_v(q, d);
 			move_v(q.step(Direction('<')), d);
 		}
 		(*this)[q] = (*this)[p];
 		(*this)[p] = '.';
 		return true;
 	}
 
 	bool isfree_v(Position p, Direction d) {
 		auto q = p.step(d);
 		switch ((*this)[q]) {
 		case '.':
 			return true;
 		case ']':
 			return isfree_v(q, d) &&
 			       isfree_v(q.step(Direction('<')), d);
 		case '[':
 			return isfree_v(q, d) &&
 			       isfree_v(q.step(Direction('>')), d);
 		default:
 			return false;
 		}
 		if ((*this)[q] == '.')
 			return true;
 	}
 };
 
 int main() {
 	string line;
 	vector<string> lines;
 
 	for (getline(cin, line); line.size() > 0; getline(cin, line)) {
 		string wideline = "";
 		for (const auto& c : line) {
 			switch (c) {
 			case 'O':
 				wideline += "[]";
 				break;
 			case '@':
 				wideline += "@.";
 				break;
 			default:
 				wideline += c;
 				wideline += c;
 				break;
 			}
 		}
 		lines.push_back(wideline);
 	}
 	Board board(lines);
 
 	while (getline(cin, line))
 		for (const auto& c : line)
 			board.move_robot(Direction(c));
 
 	cout << board.gps() << endl;
 
 	return 0;
 }