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# 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. | ||
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class Matrix: # 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 | ||
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def __eq__(self, other): | ||
return self.graph == other.graph | ||
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def is_safe(self, i: int, j: int, visited: list[list[bool]]) -> bool: | ||
return ( | ||
0 <= i < self.ROW | ||
and 0 <= j < self.COL | ||
and not visited[i][j] | ||
and self.graph[i][j] | ||
) | ||
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def diffs(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 | ||
for k in range(8): | ||
if self.is_safe(i + row_nbr[k], j + col_nbr[k], visited): | ||
self.diffs(i + row_nbr[k], j + col_nbr[k], visited) | ||
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def count_islands(self) -> int: # And finally, count all islands. | ||
visited = [[False for j in range(self.COL)] for i in range(self.ROW)] | ||
count = 0 | ||
for i in range(self.ROW): | ||
for j in range(self.COL): | ||
if visited[i][j] is False and self.graph[i][j] == 1: | ||
self.diffs(i, j, visited) | ||
count += 1 | ||
return count |
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