c++实现skip list

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编程实例：
#include <iostream>#include <cstdio>#include <unistd.h>#include <cstdlib>#include <time.h>#define maxLevel 12struct Node{int key;int value;Node* forward[1];};struct skipList{int level;Node* head;};class SkipList{public:    SkipList(){srand((int)time(0)); slist = (skipList*)malloc(sizeof(skipList));slist->head = createNode(maxLevel, 0, 0);slist->level = 0;for(int i=0; i<maxLevel; ++i){slist->head->forward[i] = NULL;}}int search(int key){Node *p, *q;p = slist->head;int k = slist->level;        for(int i=k; i>=0; --i){while(p->forward[i] != NULL && p->forward[i]->key <= key){if(p->forward[i]->key == key){q = p->forward[i];return q->value;}p = p->forward[i];}}}bool insert(int key, int value){Node *p, *q;Node *update[maxLevel];p = slist->head;int k = slist->level;for(int i = k; i>=0; --i){while(p->forward[i] != NULL && p->forward[i]->key < key){p = p->forward[i];}update[i] = p;}q = p->forward[0];if(q && q->key == key)return false;k = random();if(k > slist->level){for(int i=slist->level; i<=k; ++i){update[i] = slist->head;}slist->level = k;}q = createNode(k, key, value);for(int i = 0; i<=k; ++i){q->forward[i] = update[i]->forward[i];update[i]->forward[i] = q;}printList();}bool remove(int key){Node *update[maxLevel];  Node *p,*q;  p = slist->head;  int k = slist->level;  for(int i = k ; i >=0 ; i --){  while(p->forward[i] != NULL && (p->forward[i]->key < key)){  p = p->forward[i];  }  update[i] = p;  }  q = p->forward[0];  if(q && q->key == key){  for(int i = 0 ; i <= k; ++i){  if(update[i]->forward[i] != q)  break;  update[i]->forward[i] = q->forward[i];  }  free(q);  for(int i = slist->level ; i > 0 ; i --){  if(slist->head->forward[i] == NULL){  slist->level --;  }  }//printList();return true;  }  else{  return false;  }  }    virtual ~SkipList(){destroy();}private:Node* createNode(int level, int key, int value){Node* node = (Node*)malloc(sizeof(Node) + level*sizeof(Node*));node->key = key;node->value = value;return node;}int random(){int k = 0;while(rand() %2) k++;k = k>maxLevel?maxLevel:k;return k;}void printList(){Node *p,*q;  int k=slist->level;  for(int i=k; i >= 0; i--)  {  p = slist->head->forward[i];  printf("level[%d]: ",i);  while(p->forward[i] != NULL)  {  printf("%d -> ",p->value);  p = p->forward[i];  }  printf("%d\n",p->value);  }  printf("\n");  }void destroy(){Node *p, *q;int k = slist->level;p = slist->head;for(int i= k; i>=0; --i){while((q = p) !=NULL){free(q);p = p->forward[i];}}free(slist);slist = NULL;}private:    skipList* slist;};int main(){SkipList skip;for(int i=1; i<20; ++i){skip.insert(i, 2*i);}int v = skip.search(5);std::cout << v << "\n";skip.remove(5);std::cout << skip.search(5)<< "\n";sleep(2);    return 0;  }
编译：g++ -g -o testSkip skip.cpp
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