Islands.py

matrix = [
	[0, 1, 1, 0, 1, 1, 0],
	[0, 1, 1, 0, 1, 1, 0],
	[0, 0, 0, 0, 0, 1, 0],
	[0, 1, 1, 1, 0, 0, 1],
	[0, 0, 0, 0, 1, 1, 1]
]

blankMatrix = [
	[0, 0, 0, 0, 0, 0, 0],
	[0, 0, 0, 0, 0, 0, 0],
	[0, 0, 0, 0, 0, 0, 0],
	[0, 0, 0, 0, 0, 0, 0],
	[0, 0, 0, 0, 0, 0, 0]
]

# Results
tmpSize = 1 # Size is 1 to account for initial element
sizes = []
numOfIslands = 0

def checkNeighbor(row, column):
	# If island and not visited
	if matrix[row][column] == 1 and blankMatrix[row][column] != 1:
		
		# Update copy
		blankMatrix[row][column] = 1
		
		# Increase size
		global tmpSize
		tmpSize += 1
		
		# Recurse neigbors
		visitNeighbors(row, column)



def visitNeighbors(row, column):
	# Top left
	if (row - 1 >= 0 and column - 1 >= 0):
		checkNeighbor(row - 1, column - 1)
	
	# Top
	if (row - 1 >= 0):
		checkNeighbor(row - 1, column)
	
	# Top right
	if (row - 1 >= 0 and column + 1 < len(matrix[0])):
		checkNeighbor(row - 1, column + 1)
	
	# Left
	if (column - 1 >= 0):
		checkNeighbor(row, column - 1)
	
	# Right
	if (column + 1 < len(matrix[0])):
		checkNeighbor(row, column + 1)
	
	# Bottom left
	if (row + 1 < len(matrix) and column - 1 >= 0):
		checkNeighbor(row + 1, column - 1)
	
	# Bottom
	if (row + 1 < len(matrix)):
		checkNeighbor(row + 1, column)
	
	# Bottom right
	if (row + 1 < len(matrix) and column + 1 < len(matrix[0])):
		checkNeighbor(row + 1, column + 1)
	

# Iterators
currentRow = 0
currentIndex = 0

for row in matrix: 										# iterate each row
	for val in row: 									# iterate
		if blankMatrix[currentRow][currentIndex] == 0:	# check if visited (perf)
			if matrix[currentRow][currentIndex] == 1:
				
				# Update copy
				blankMatrix[currentRow][currentIndex] = 1
				
				# Recurse neighbors
				visitNeighbors(currentRow, currentIndex)
				
				# Add island and size of island
				sizes.append(tmpSize)
				tmpSize = 1 # Size is 1 to account for initial element
				numOfIslands += 1			
				
		currentIndex += 1
	currentRow += 1
	currentIndex = 0
				
print("Number of islands: {0}".format(numOfIslands))
print("Biggest island: {0}".format(max(sizes)))