FloodFill

# Matrix has border where each element is 1
def FloodFill(matrix, i, j):
    if matrix[i][j] != 0:
        return

    # Changing of visited field (Matrix is 0 and 1)
    matrix[i][j] = 2

    FloodFill(matrix, i, j + 1)
    FloodFill(matrix, i, j - 1)
    FloodFill(matrix, i - 1, j)
    FloodFill(matrix, i + 1, j)