2020aoc/Day11.java

package dev.forstenlechner.aoc;

import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;

public class Day11 {

    private enum SeatState {
        EMPTY {
            @Override
            void print() {
                System.out.print("L");
            }
        }, OCCUPIED {
            @Override
            void print() {
                System.out.print("#");
            }
        }, FLOOR {
            @Override
            void print() {
                System.out.print(".");
            }
        };

        abstract void print();

        static SeatState from(char c) {
            return switch (c) {
                case 'L' -> EMPTY;
                case '#' -> OCCUPIED;
                default -> FLOOR;
            };
        }
    }

    private record Location(int row, int col) {};

    private enum Directon {
        UP {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() -1, cur.col);
            }
        }, DOWN {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() +1, cur.col);
            }
        }, LEFT{
            @Override
            Location next(Location cur) {
                return new Location(cur.row(), cur.col -1);
            }
        }, RIGHT{
            @Override
            Location next(Location cur) {
                return new Location(cur.row(), cur.col +1);
            }
        }, LEFT_UP {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() -1, cur.col -1);
            }
        }, LEFT_DOWN {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() +1, cur.col -1);
            }
        }, RIGHT_UP {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() -1, cur.col +1);
            }
        }, RIGHT_DOWN {
            @Override
            Location next(Location cur) {
                return new Location(cur.row() +1, cur.col +1);
            }
        };

        abstract Location next(Location cur);
    }

    public static void main(String[] args) throws Exception {
        new Day11().solve();
    }

    private List<List<SeatState>> copySeatMap(List<List<SeatState>> seatMap) {
        return seatMap.stream().map(ArrayList::new).collect(toList());
    }

    private void solve() throws Exception {
        Stream<String> lines = Files.lines(Paths.get("day11/input"));
        List<List<SeatState>> seatMap = lines
                .map(l -> l.chars().mapToObj(c -> (char) c).map(SeatState::from).collect(toList()))
                .collect(toList());

        solveFirst(seatMap);

        solveSecond(seatMap);
    }

    private void printMap(List<List<SeatState>> seatMap) {
        seatMap.forEach(row -> {
            row.forEach(SeatState::print);
            System.out.println();
        });
    }

    private void solveSecond(List<List<SeatState>> seatMap) {
        boolean changed = true;
        while (changed) {
//            printMap(seatMap);
//            System.out.println();
            changed = false;
            var nextSeatMap = copySeatMap(seatMap);
            for (int row = 0; row < seatMap.size(); row++) {
                for (int column = 0; column < seatMap.get(row).size(); column++) {
                    SeatState prev = seatMap.get(row).get(column);
                    SeatState next = calcSeatWithDirection(seatMap, row, column);
                    changed |= prev != next;
                    nextSeatMap.get(row).set(column, next);
                }
            }
            seatMap = nextSeatMap;
        }

        Long occupiedSeats = seatMap.stream().map(col -> col.stream().filter(state -> state == SeatState.OCCUPIED).count()).reduce(0L, Long::sum);
        System.out.println(occupiedSeats);
    }

    private void solveFirst(List<List<SeatState>> seatMap) {
        boolean changed = true;
        while (changed) {
            changed = false;
            var nextSeatMap = copySeatMap(seatMap);
            for (int row = 0; row < seatMap.size(); row++) {
                for (int column = 0; column < seatMap.get(row).size(); column++) {
                    SeatState prev = seatMap.get(row).get(column);
                    SeatState next = calcSeat(seatMap, row, column);
                    changed |= prev != next;
                    nextSeatMap.get(row).set(column, next);
                }
            }
            seatMap = nextSeatMap;
        }

        Long occupiedSeats = seatMap.stream().map(col -> col.stream().filter(state -> state == SeatState.OCCUPIED).count()).reduce(0L, Long::sum);
        System.out.println(occupiedSeats);
    }

    private SeatState calcSeat(List<List<SeatState>> seatMap, int row, int column) {
        int occupiedSeatsAround = 0;
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row-1, column-1);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row-1, column);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row-1, column+1);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row+1, column-1);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row+1, column);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row+1, column+1);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row, column-1);
        occupiedSeatsAround += isSeatOccupiedInt(seatMap, row, column+1);

        if (seatMap.get(row).get(column) == SeatState.EMPTY && occupiedSeatsAround == 0) {
            return SeatState.OCCUPIED;
        }
        if (seatMap.get(row).get(column) == SeatState.OCCUPIED && occupiedSeatsAround >= 4) {
            return SeatState.EMPTY;
        }
        return seatMap.get(row).get(column);
    }

    private int isSeatOccupiedInt(List<List<SeatState>> seatMap, int row, int column) {
        if (row >= 0 && row < seatMap.size()
            && column >= 0 && column < seatMap.get(row).size()) {
            return seatMap.get(row).get(column) == SeatState.OCCUPIED ? 1 : 0;
        }
        return 0;
    }
























    private SeatState calcSeatWithDirection(List<List<SeatState>> seatMap, int row, int column) {
        int occupiedSeatsAround = 0;
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.UP);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.DOWN);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.LEFT);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.RIGHT);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.LEFT_UP);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.LEFT_DOWN);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.RIGHT_UP);
        occupiedSeatsAround += isSeatOccupiedIntWithDirection(seatMap, row, column, Directon.RIGHT_DOWN);

        if (seatMap.get(row).get(column) == SeatState.EMPTY && occupiedSeatsAround == 0) {
            return SeatState.OCCUPIED;
        }
        if (seatMap.get(row).get(column) == SeatState.OCCUPIED && occupiedSeatsAround >= 5) { // change in rule!
            return SeatState.EMPTY;
        }
        return seatMap.get(row).get(column);
    }

    private int isSeatOccupiedIntWithDirection(List<List<SeatState>> seatMap, int row, int column, Directon directon) {
        return isSeatOccupiedIntWithDirection(seatMap, new Location(row, column), directon);
    }

    private int isSeatOccupiedIntWithDirection(List<List<SeatState>> seatMap, Location test, Directon directon) {
        test = directon.next(test);
        while (test.row() >= 0 && test.row() < seatMap.size()
                && test.col() >= 0 && test.col() < seatMap.get(test.row()).size()
                && seatMap.get(test.row).get(test.col()) == SeatState.FLOOR) {
            test = directon.next(test);
        }
        if (test.row() >= 0 && test.row() < seatMap.size()
                && test.col() >= 0 && test.col() < seatMap.get(test.row()).size()) {
            return seatMap.get(test.row()).get(test.col()) == SeatState.OCCUPIED ? 1 : 0;
        }
        return 0;
    }
}