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Changed matrix initialisation in count_islands_in_matrix.py. Addressing requested changes on #12555

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CheerfulBear22 2025-02-04 19:20:43 +00:00
parent 6c92c5a539
commit 16bb4b50e4
1 changed files with 67 additions and 6 deletions
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73
matrix/count_islands_in_matrix.py
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@ -4,12 +4,45 @@
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
def __init__(self, graph: list[list[bool]]) -> None:
"""
Initialise matrix with number of rows, columns, and graph.
>>> m = Matrix([[True, False, False, False],
... [True, False, True, False],
... [False, False, True, True]])
>>> m.ROW
3
>>> m.COL
4
>>> m.graph
[[True, False, False, False],
[True, False, True, False],
[False, False, True, True]]
"""
self.graph = graph
self.ROW = len(graph)
self.COL = len(graph[0])
def is_safe(self, i: int, j: int, visited: list[list[bool]]) -> bool:
"""
Checks if the cell (i, j) can be visited.
>>> visited = [[False, False, False],
... [False, False, False],
... [False, False, False]]
>>> m = Matrix([[True, False, False],
... [False, False, True],
... [False, False, True]])
>>> m.is_safe(0, 0, visited)
True
>>> m.is_safe(0, 2, visited)
False
>>> m.is_safe(-1, 2, visited)
False
>>> m.is_safe(1, 5, visited)
False
"""
return (
0 <= i < self.ROW
and 0 <= j < self.COL
@ -18,7 +51,21 @@ class Matrix: # Public class to implement a graph
)
def diffs(self, i: int, j: int, visited: list[list[bool]]) -> None:
# Checking all 8 elements surrounding nth element
"""
Checking all 8 elements surrounding nth element.
>>> visited = [[False, False, False],
... [False, False, False],
... [False, False, False]]
>>> m = Matrix([[True, True, False],
... [False, True, False],
... [True, False, True]])
>>> m.diffs(0, 0, visited)
>>> visited
[[True, True, False],
[False, True, False],
[True, False, True]]
"""
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
@ -26,12 +73,26 @@ class Matrix: # Public class to implement a graph
if self.is_safe(i + row_nbr[k], j + col_nbr[k], visited):
self.diffs(i + row_nbr[k], j + col_nbr[k], visited)
def count_islands(self) -> int: # And finally, count all islands.
def count_islands(self) -> int:
"""
Counts the number of islands in the matrix.
>>> m = Matrix([[True, True, False, False],
... [False, True, False, True],
... [True, False, False, True]])
>>> m.count_islands()
2
>>> m2 = Matrix([[True, True, False],
... [True, False, False],
... [False, False, True]])
>>> m2.count_islands()
2
"""
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:
if visited[i][j] is False and self.graph[i][j]:
self.diffs(i, j, visited)
count += 1
return count