斐波那契树完成插入和extra_min

Author: ssjssh

src/ssj/heap/fibonacci_heap.py

@@ -0,0 +1,168 @@
+#!/usr/bin/env python
+# -*- coding:UTF-8
+__author__ = 'shenshijun'
+
+
+class FibonacciHeap(object):
+    """实现斐波那契堆,斐波那契堆在一些操作执行的时候负责度比较低，而其他操作的复杂度和普通的堆是一样的"""
+
+    class Node(object):
+        """节点实现"""
+
+        def __init__(self, key, parent=None, child=None, left=None, right=None):
+            """Constructor for """
+            self.key = key
+            self.degree = 0
+            self.mark = False
+            self.parent = parent
+            self.child = child
+            self.left = left or self
+            self.right = right or self
+
+        def __str__(self):
+            return str(self.key) + " : " + str(self.degree)
+
+    def __init__(self, *argv):
+        """Constructor for """
+        self.__root = None
+        self.__size = 0
+        map(self.insert, argv)
+
+    def insert(self, key):
+        self.__size += 1
+        if self.__root is None:
+            self.__root = self.Node(key)
+        else:
+            new_node = self.Node(key, left=self.__root.left, right=self.__root)
+            self.__root.left.right = new_node
+            self.__root.left = new_node
+            if new_node.key < self.__root.key:
+                self.__root = new_node
+
+    def extract_min(self):
+        if self.__root is None:
+            return None
+
+        result = self.__root
+        self.__size -= 1
+
+        # 首先把根节点的子节点全部移到根链表上
+        child = self.__root.child
+        for i in xrange(0, self.__root.degree):
+            next_node = child.right
+            self.__root.left.right = child
+            child.left = self.__root.left
+            self.__root.left = child
+            child.right = self.__root
+            child.parent = None
+            child = next_node
+
+        # 移除根节点
+        self.__root.left.right = self.__root.right
+        self.__root.right.left = self.__root.left
+        if self.__root.right is self.__root:
+            self.__root = None
+        else:
+            self.__root = self.__root.right
+            self.__extract_consolidating()
+
+        return result.key
+
+    def __extract_consolidating(self):
+        # 合并根链表
+        node_degrees = {}
+        pass_root = False
+        cur_node = self.__root
+        after_merge = False
+        next_node = None
+        while cur_node is not self.__root or not pass_root or after_merge:
+            if cur_node == self.__root:
+                pass_root = True
+
+            if not after_merge:
+                next_node = cur_node.right
+
+            d = cur_node.degree
+            if d in node_degrees:
+                other_node = node_degrees[d]
+                sm_node = cur_node if cur_node.key <= other_node.key else other_node
+                bg_node = cur_node if cur_node.key > other_node.key else other_node
+                # 把大的节点连接到小的节点上面,然后继续在sm_node上面循环，因为sm_node的度数发生了变化
+                self.__link_to(bg_node, sm_node)
+                del node_degrees[d]
+                after_merge = True
+                cur_node = sm_node
+            else:
+                after_merge = False
+                node_degrees[d] = cur_node
+                cur_node = next_node
+
+        self.__root = None
+
+        for d, node in node_degrees.iteritems():
+            node.parent = None
+            if self.__root is None:
+                self.__root = node
+                self.__root.left = node
+                self.__root.right = node
+            else:
+                node.left = self.__root.left
+                node.right = self.__root
+                self.__root.left.right = node
+                self.__root.left = node
+
+            if self.__root.key > node.key:
+                self.__root = node
+
+    @staticmethod
+    def __link_to(src, dest):
+        """
+         bugfix: 不能把src从根链表移除,这样的话会破坏根链表，导致在__extract_consolidating中的while找不到退出条件
+         我是为了避免重新创建根链表而把src从根链表中移除，这段注释只是为了提醒
+        :param src:
+        :param dest:
+        :return:
+        """
+        src.mark = False
+
+        dest_child = dest.child
+        src.parent = dest
+        if dest_child is None:
+            dest.child = src
+            src.left = src
+            src.right = src
+        else:
+            src.left = dest_child.left
+            dest_child.left.right = src
+            dest_child.left = src
+            src.right = dest_child
+        dest.degree += 1
+
+    def union(self, other):
+        pass
+
+    def min(self):
+        return None if self.__root is None else self.__root.key
+
+    def change_key(self, node, new_key):
+        pass
+
+    def __len__(self):
+        return self.__size
+
+    def delete(self, node):
+        self.change_key(node, float('-Inf'))
+        self.extract_min()
+
+
+def main():
+    test = ['O', 'J', 'S', 'Y', 'C', 'M', 'B', 'R', 'N', 'F', 'L', 'Z', 'U', 'Q', 'A', 'G', 'V', 'E', 'D', 'W', 'I',
+            'H', 'T', 'K', 'X', 'P']
+
+    heap = FibonacciHeap(*test)
+    for i in xrange(0, len(heap)):
+        print(heap.extract_min())
+
+
+if __name__ == "__main__":
+    main()