private static final int EMPTY_CELL = 0;

private static final int FRESH_ORANGE = 1;

private static final int ROTTEN_ORANGE = 2;

private static final class Orange {

private final int row;

private final int column;

private final int minutes;

private Orange(int row, int column, int minutes) {

this.row = row;

this.column = column;

this.minutes = minutes;

}

@Override

public boolean equals(Object obj) {

if (obj == this) return true;

if (obj == null || obj.getClass() != this.getClass()) return false;

var that = (Orange) obj;

return this.row == that.row && this.column == that.column;

}

@Override

public int hashCode() {

return Objects.hash(row, column);

}

}

public static int orangesRotting(int[][] grid) {

final Queue<Orange> oranges = allRottingOranges(grid);

final Set<Orange> visited = new HashSet<>();

int result = 0;

while (!oranges.isEmpty()) {

Orange orange = oranges.poll();

if (!isValidPosition(orange, grid) || visited.contains(orange) || isEmptyCell(grid, orange)) {

continue;

}

visited.add(orange);

grid[orange.row][orange.column] = ROTTEN_ORANGE;

oranges.add(new Orange(orange.row - 1, orange.column, orange.minutes + 1));

oranges.add(new Orange(orange.row, orange.column + 1, orange.minutes + 1));

oranges.add(new Orange(orange.row + 1, orange.column, orange.minutes + 1));

oranges.add(new Orange(orange.row, orange.column - 1, orange.minutes + 1));

result = Math.max(result, orange.minutes);

}

if (allAreRotten(grid)) return result;

return -1;

}

private static boolean allAreRotten(int[][] grid) {

for (int[] row : grid) {

for (int orange : row) {

if (orange == FRESH_ORANGE) return false;

}

}

return true;

}

private static Queue<Orange> allRottingOranges(int[][] grid) {

final Queue<Orange> rottenOranges = new LinkedList<>();

for (int row = 0 ; row < grid.length ; row++) {

for (int column = 0 ; column < grid[0].length ; column++) {

if (grid[row][column] == ROTTEN_ORANGE) {

rottenOranges.add(new Orange(row, column, 0));

}

}

}

return rottenOranges;

}

private static boolean isValidPosition(Orange orange, int[][] grid) {

return orange.row >= 0 && orange.row < grid.length && orange.column >= 0 && orange.column < grid[0].length;

}

private static boolean isRotten(int[][] grid, Orange orange) {

return grid[orange.row][orange.column] == ROTTEN_ORANGE;

}

private static boolean isEmptyCell(int[][] grid, Orange orange) {

return grid[orange.row][orange.column] == EMPTY_CELL;

}