def delete_and_splay(self, key):
""" After regular BST delete, the former node's parent is hoisted to
the root.
"""
removed = BST.delete(self, key)
self.splay(removed[PARENT])
return removed
def delete_and_splay(self, key):
""" After regular BST delete, the former node's parent is hoisted to
the root.
"""
removed = BST.delete(self, key)
self.splay(removed[PARENT])
return removed
def delete_and_reballance(self, key):
# Node is a recently removed leaf.
node = BST.delete(self, key)
if node == None:
return None
ancestor = node
while ancestor != None:
ancestor = ancestor[PARENT]
# Ignore ballanced ancestors.
if -2 < self.get_ballance_factor(ancestor) < 2:
continue
if self.depth(ancestor[LEFT]) > self.depth(ancestor[RIGHT]):
FIRST = LEFT
else:
FIRST = RIGHT
if self.depth(ancestor[FIRST][LEFT]) > self.depth(ancestor[FIRST][RIGHT]):
SECOND = LEFT
else:
SECOND = RIGHT
#import pdb; pdb.set_trace()
self.reballance(ancestor[FIRST][SECOND])
return node
