Ejemplo n.º 1
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 def min(self):
     """Return but do not remove (k, v) tuple with minimum key."""
     if self.is_empty():
         raise Empty('Priority queue is empty')
     p = self._data.first()
     item = p.element()
     return (item._key, item._value)
Ejemplo n.º 2
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    def top(self):
        """Return (but do not remove) the element at the top of the stack.

        Raise Empty exception if the stack is empty.
        """
        if self.is_empty():
            raise Empty('Stack is empty')
        return self._head._element  # top of stack is at head of list
Ejemplo n.º 3
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    def first(self):
        """Return (but do not remove) the element at the front of the queue.

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        return self._head._element  # front aligned with head of list
Ejemplo n.º 4
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    def delete_last(self):
        """Remove and return the element from the back of the deque.

        Raise Empty exception if the deque is empty.
        """
        if self.is_empty():
            raise Empty('Deque is empty')
        return self._delete_node(self._trailer._prev)  # use inherited method
Ejemplo n.º 5
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    def delete_first(self):
        """Remove and return the element from the front of the deque.

        Raise Empty exception if the deque is empty.
        """
        if self.is_empty():
            raise Empty('Deque is empty')
        return self._delete_node(self._header._next)  # use inherited method
Ejemplo n.º 6
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    def first(self):
        """Return (but do not remove) the element at the front of the queue.

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        return self._data[self._front]
Ejemplo n.º 7
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    def min(self):
        """Return but do not remove (k, v) tuple with minimum key.

        Raise Empty exception if empty.
        """
        if self.is_empty():
            raise Empty('Priority queue is empty')
        item = self._data[0]
        return (item._key, item._value)
Ejemplo n.º 8
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    def last(self):
        """Return (but do not remove) the element at the back of the deque.

        Raise Empty exception if the deque is empty.
        """
        if self.is_empty():
            raise Empty('Deque is empty')
        back = (self._front + self._size - 1) % len(self._data)
        return self._data[back]
Ejemplo n.º 9
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    def first(self):
        """Return (but do not remove) the element at the front of the queue.

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        head = self._tail._next
        return head._element
Ejemplo n.º 10
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 def _find_min(self):                                # nonpublic utility
     """Return Position of item with minimum key."""
     if self.is_empty():                                # is_empty inherited from base class
         raise Empty('Priority queue is empty')
     small = self._data.first()
     walk = self._data.after(small)
     while walk is not None:
         if walk.element() < small.element():
             small = walk
         walk = self._data.after(walk)
     return small
Ejemplo n.º 11
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    def pop(self):
        """Remove and return the element from the top of the stack (i.e. LIFO).

        Raise Empty exception if the stack is empty.
        """
        if self.is_empty():
            raise Empty('Stack is empty')
        answer = self._head._element
        self._head = self._head._next  # bypass the former top node
        self._size -= 1
        return answer
Ejemplo n.º 12
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    def remove_min(self):
        """Remove and return (k, v) tuple with minimum key.

        Raise Empty exception if empty.
        """
        if self.is_empty():
            raise Empty('Priority queue is empty')
        self._swap(0, len(self._data) - 1)  # put minimum item at the end
        item = self._data.pop()  # and remove it from the list;
        self._downheap(0)  # then fix new root
        return (item._key, item._value)
Ejemplo n.º 13
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    def dequeue(self):
        """Remove and return the first element of the queue (i.e. FIFO).

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        answer = self._head._element
        self._head = self._head._next
        self._size -= 1
        if self.is_empty():  # special case as queue is empty
            self._tail = None  # removed head had been the tail
        return answer
Ejemplo n.º 14
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    def dequeue(self):
        """Remove and return the first element of the queue (i.e. FIFO).

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        answer = self._data[self._front]
        self._data[self._front] = None  # help garbage collection
        self._front = (self._front + 1) % len(self._data)
        self._size -= 1
        if 0 < self._size < len(self._data) // 4:
            self._resize(len(self._data) // 2)
        return answer
Ejemplo n.º 15
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    def dequeue(self):
        """Remove and return the first element of the queue (i.e. FIFO).

        Raise Empty exception if the queue is empty.
        """
        if self.is_empty():
            raise Empty('Queue is empty')
        oldhead = self._tail._next
        if self._size == 1:  # removing only element
            self._tail = None  # queue becomes empty
        else:
            self._tail._next = oldhead._next  # bypass the old head
        self._size -= 1
        return oldhead._element
Ejemplo n.º 16
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    def delete_last(self):
        """Remove and return the last element of the deque.

        Raise Empty exception if the deque is empty.
        """
        if self.is_empty():
            raise Empty('Deque is empty')
        back = (self._front + self._size - 1) % len(self._data)
        answer = self._data[back]
        self._data[back] = None  # help garbage collection
        self._size -= 1
        if 0 < self._size < len(self._data) // 4:
            self._resize(len(self._data) // 2)
        return answer
Ejemplo n.º 17
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 def last(self):
     """Return (but do not remove) the element at the back of the deque."""
     if self.is_empty():
         raise Empty('Deque is empty')
     return self._trailer._prev._element  # real item just before trailer
Ejemplo n.º 18
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 def remove_min(self):
     """Remove and return (k, v) tuple with minimum key."""
     if self.is_empty():
         raise Empty('Priority queue is empty')
     item = self._data.delete(self._data.first())
     return (item._key, item._value)