Count

matrix/count_islands_in_matrix.py

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+# An island in matrix is a group of linked areas, all having the same value. 
+# This code couts number of islands in a given matrix, with including diagonal connections.
+
+class matrix: # Public class to implement a graph
+
+	def __init__(self, row, col, g): # Class constructor
+		self.ROW = row 
+		self.COL = col 
+		self.graph = g
+
+	def is_safe(self, i, j, visited): 
+		return (i >= 0 and i < self.ROW and j >= 0 and j < self.COL and not visited[i][j] and self.graph[i][j]) 
+
+	def diffs(self, i, j, visited): # Checking all 8 elements surrounding nth element
+
+		rowNbr = [-1, -1, -1, 0, 0, 1, 1, 1]; # Coordinate order
+		colNbr = [-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 + rowNbr[k], j + colNbr[k], visited): 
+				self.diffs(i + rowNbr[k], j + colNbr[k], visited) 
+
+
+	def count_islands(self): # And finally, count all islandas.
+		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] == False and self.graph[i][j] == 1: 
+					self.diffs(i, j, visited) 
+					count += 1
+		return count 
+