更新了跳表

Author: LuYanFCP

cpp/数据结构/ShipList.cpp

@@ -0,0 +1,124 @@
+#include <cstdlib>
+#include <cmath>
+#include <vector>
+#include "ShipList.h"
+
+using std::rand;
+using std::ceil;
+using std::log;
+using std::vector;
+
+int ShipList::randLevel()
+{
+    int level = 1;
+    for (;rand() < p && maxLevel; level++);
+    return level;
+}
+
+ShipList::ShipList(double _p, int _maxN) 
+{
+    p = _p;
+    maxN = _maxN;
+    maxLevel = static_cast<int>(ceil(log(_maxN) / log(1/p)));
+    forward = vector<Node*>(maxLevel+1, nullptr);  // 使用拷贝构造进行初始化
+
+}
+
+int 
+ShipList::Search(int _key)
+{
+
+    // 出循环的时候已经到达最后一层
+    vector<Node*>& p = forward;
+    for (int i = maxLevel; i > 0; --i) {
+        if (!p[i]) continue;
+        if (p[i]->key < _key)
+            p = p[i]->forward;
+        else if (p[i]->key == _key)
+            return p[i]->key;
+    }
+    while (1) {
+        if (p[1]->key == _key) {
+            return p[1]->key;
+        } else if (p[1]->key < _key) {
+            return -1;
+        }
+        p = p[1]->forward;
+    }
+    return -1;
+}
+
+void 
+ShipList::Insert(int _key)
+{
+    vector<Node*> update(maxLevel, nullptr); // 用于更新
+    vector<Node*>& p = forward;
+    for (int i = maxLevel; i > 0; --i) {
+        if (!p[i]) continue;
+        if (p[i]->key < _key) {
+            update[i] = p[i];
+            p = p[i]->forward;
+        }
+        else if (p[i]->key == _key)
+            return ; // 因为出现相等了
+    }
+
+    // 循环找插入节点
+    while (1) {
+        if (p[1]->key < _key) {
+            update[1] = p[1];
+            p = p[1]->forward;
+        } else if (p[1]->key == _key) {
+            return; // 直接返回
+        } else break; 
+    }
+    
+    /**
+     *  创建节点:
+     *  1. 随机选randlevel
+     *  2. new节点
+     *  3. 更新具体链表信息
+     */
+    int level = randLevel();
+    Node* newNode = new Node(level, _key);
+    p = newNode->forward;
+    for (int i = 1; i <= level; ++i) {
+        p[i] = update[i]->forward[i];
+        update[i]->forward[i] = newNode;
+    }
+}
+
+void 
+ShipList::Delete(int _key) 
+{
+    if (Search(_key) < 0) return;
+    vector<Node*> update(maxLevel, nullptr); // 用于更新
+    vector<Node*>& p = forward;
+    for (int i = maxLevel; i > 0; --i) {
+        if (!p[i]) continue;
+        if (p[i]->key < _key) {
+            update[i] = p[i];
+            p = p[i]->forward;
+        }
+        else if (p[i]->key == _key)
+            return ; // 因为出现相等了
+    }
+
+    // 循环找插入节点
+    while (1) {
+        if (p[1]->key < _key) {
+            update[1] = p[1];
+            p = p[1]->forward;
+        } else
+            break; // =等于跳出循环
+    }
+
+    // 找到的离开该最近的节点
+    // p是forward的引用
+    int level = update[1]->forward.size();
+    Node* delPtr = update[1];
+    for (int i = 1; i <= level; ++i) {
+        update[i]->forward[i] = p[i];
+    }
+    delete delPtr;
+}

cpp/数据结构/ShipList.h

@@ -0,0 +1,29 @@
+#include <vector>
+using std::vector;
+
+
+struct Node 
+{
+    int k; // 表示它的阶数
+    int key; // key value
+    vector<Node*> forward;
+    Node()=default;
+    Node(int _k, int _key): k(_k), key(_key) {forward.push_back(nullptr);};
+};
+
+class ShipList
+{
+public:
+    ShipList()=default;
+    ShipList(double _p, int _maxN);
+    int Search(int _key);  // 这类做简化，只返回key，而不是指针和具体的value
+    void Insert(int _key);
+    void Delete(int _key);
+private:
+    int randLevel();
+    double p;
+    int maxLevel;
+    int maxN;
+    vector<Node*> forward; 
+    Node* _search(Node* node, int _key);
+};