def buildTree(numbers, availableSpace, total, previousNode):
tree = []
nodeIsValid = True
# print initial status
numberOfItems = len(numbers)
print(" ")
print("numbers: ", numbers)
print(
"calculating the possible combinations: for a maximum capacity of %i" %
availableSpace)
if (numberOfItems == 0):
print("skipping empty list of numbers")
node = []
elif (numberOfItems == 1):
value = numbers[0]
# recalculate available and used space
if (availableSpace >= value):
availableSpace = availableSpace - value
total = total + value
else:
# the required space is too small
nodeIsValid = False
# initiate a new node
node = TreeNode(value, availableSpace, total)
print("added new node:", value)
if (nodeIsValid == False):
print("node is invalid")
node.setInvalid()
else:
node.setValid()
print("available space left: %i" % availableSpace)
print("space in use:", total)
else:
# calculate the middlest item
nodePosition = int(numberOfItems / 2)
value = numbers[nodePosition]
# recalculate available and used space
if (availableSpace >= value):
availableSpace = availableSpace - value
total = total + value
else:
# the required space is too small
nodeIsValid = False
# initiate this node as a new node
node = TreeNode(value, availableSpace, total)
print("added new node:", value)
if (nodeIsValid == False):
print("node is invalid")
node.setInvalid()
else:
node.setValid()
print("available space left: %i" % availableSpace)
print("space in use:", total)
# calculate subtree for the numbers left of the node value
leftSubtree = buildTree(numbers[0:nodePosition], availableSpace, total,
node)
if (len(leftSubtree)):
firstNode = leftSubtree[0]
if isinstance(firstNode, TreeNode):
if (firstNode.isInvalidNode()):
# invalid nodes belong to the right side
node.setRight(leftSubtree)
else:
# valid nodes belong to the left side
node.setLeft(leftSubtree)
# calculate subtree for the numbers right of the node value
if (nodePosition < numberOfItems):
rightSubtree = buildTree(numbers[nodePosition + 1:],
availableSpace, total, node)
else:
rightSubtree = []
if (len(rightSubtree)):
firstNode = rightSubtree[0]
if isinstance(firstNode, TreeNode):
if (firstNode.isInvalidNode()):
# invalid nodes belong to the right side
node.setRight(rightSubtree)
else:
# valid nodes belong to the left side
node.setLeft(rightSubtree)
# add the newly built node to the tree
tree.append(node)
print(tree)
return tree
