新增排行榜服务

util/algorithms/skip/node.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2014 Workiva, LLC
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package skip
+
+type widths []uint64
+
+type nodes []*node
+
+type node struct {
+	// forward denotes the forward pointing pointers in this
+	// node.
+	forward nodes
+	//zero level pre node
+	preNode *node
+	// widths keeps track of the distance between this pointer
+	// and the forward pointers so we can access skip list
+	// values by position in logarithmic time.
+	widths widths
+	// entry is the associated value with this node.
+	entry Comparator
+}
+
+func (n *node) Compare(e Comparator) int {
+	return n.entry.Compare(e)
+}
+
+// newNode will allocate and return a new node with the entry
+// provided.  maxLevels will determine the length of the forward
+// pointer list associated with this node.
+func newNode(cmp Comparator, maxLevels uint8) *node {
+	return &node{
+		entry:   cmp,
+		forward: make(nodes, maxLevels),
+		widths:  make(widths, maxLevels),
+	}
+}