def ceiling(self, key):
if key is None:
raise IllegalArgumentException("called ceiling() with None key")
keys = self.keys()
ceiling = None
for k in keys:
if (ceiling is None
and k >= key) or (ceiling is not None and k >= key
and k < ceiling):
ceiling = k
if ceiling is None:
raise NoSuchElementException("all keys are less than " + str(key))
return ceiling
def change_key(self, i, key):
"""
Change the key associated with index i to the specified value.
:param i: the index of the key to change
:param key: change the key associated with index i to this key
:raises IllegalArgumentException: unless 0 <= i < max_n
:raises NoSuchElementException: if no key is associated with index i
"""
if i < 0 or i >= self.max_n:
raise IllegalArgumentException("index is not within range")
if not self.contains(i):
raise NoSuchElementException("index is not in the priority queue")
self.keys[i] = key
self._swim(self.qp[i])
self._sink(self.qp[i])
def del_min(self):
"""
Removes a minimum key and returns its associated index.
:return: an index associated with a minimum key
:raises NoSuchElementException: if this priority queue is empty
:rtype: int
"""
if self.n == 0:
raise NoSuchElementException("Priority queue underflow")
_min = self.pq[1]
self._exch(1, self.n)
self.n -= 1
self._sink(1)
self.qp[_min] = -1
self.keys[_min] = None
self.pq[self.n + 1] = -1
return _min
def delete(self, i):
"""
Remove the key associated with index i
:param i: the index of the key to remove
:raises IllegalArgumentException: unless 0 <= i < max_n
:raises NoSuchElementException: if no key is associated with index i
"""
if i < 0 or i >= self.max_n:
raise IllegalArgumentException("index is not in range")
if not self.contains(i):
raise NoSuchElementException("index is not in the priority queue")
index = self.qp[i]
self._exch(index, self.n)
self.n -= 1
self._sink(index)
self.keys[i] = None
self.qp[i] = -1
def increase_key(self, i, key):
"""
Increase the key associated with index i to the specified value.
:param i: the index of the key to increase
:param key: increase the key associated with index i to this key
:raises IllegalArgumentException: unless 0 <= i < max_n
:raises IllegalArgumentException: if key <= key_of(i)
:raises NoSuchElementException: if no key is associated with index i
"""
if i < 0 or i >= self.max_n:
raise IllegalArgumentException("index is not within range")
if not self.contains(i):
raise NoSuchElementException("index is not in the priority queue")
if self.keys[i] >= key:
raise IllegalArgumentException("calling increase_key() with given argument would not strictly increase the key")
self.keys[i] = key
self._sink(self.qp[i])
def del_max(self) -> Key:
"""
Removes and returns a largest key on this priority queue.
:return: a largest key on this priority queue
:raises NoSuchElementException: if this priority queue is empty
"""
if self.is_empty():
raise NoSuchElementException("Priority queue underflow")
_max = self._pq[1]
assert _max is not None
self._exch(1, self._n)
self._n -= 1
self._sink(1)
self._pq[self._n + 1] = None
if self._n > 0 and self._n == (len(self._pq) - 1) // 4:
self._resize(len(self._pq) // 2)
return _max
def min(self):
if self.is_empty():
raise NoSuchElementException("called min() with empty set")
return min(self._set)
def max(self):
if self.is_empty():
raise NoSuchElementException("called max() with empty symbol table")
return max(self._st)