count_islands_in_matrix.py

# An island in matrix is a group of linked areas, all having the same value.
# This code counts number of islands in a given matrix, with including diagonal
# connections.


classMatrix: # Public class to implement a graph
def__init__(self, row: int, col: int, graph: list[list[bool]]) ->None:
self.ROW=row
self.COL=col
self.graph=graph

defis_safe(self, i: int, j: int, visited: list[list[bool]]) ->bool:
return (
0<=i<self.ROW
and0<=j<self.COL
andnotvisited[i][j]
andself.graph[i][j]
 )

defdiffs(self, i: int, j: int, visited: list[list[bool]]) ->None:
# Checking all 8 elements surrounding nth element
row_nbr= [-1, -1, -1, 0, 0, 1, 1, 1] # Coordinate order
col_nbr= [-1, 0, 1, -1, 1, -1, 0, 1]
visited[i][j] =True# Make those cells visited
forkinrange(8):
ifself.is_safe(i+row_nbr[k], j+col_nbr[k], visited):
self.diffs(i+row_nbr[k], j+col_nbr[k], visited)

defcount_islands(self) ->int: # And finally, count all islands.
visited= [[Falseforjinrange(self.COL)] foriinrange(self.ROW)]
count=0
foriinrange(self.ROW):
forjinrange(self.COL):
ifvisited[i][j] isFalseandself.graph[i][j] ==1:
self.diffs(i, j, visited)
count+=1
returncount