Skiplist cooooooooooooooooooool!

/*Author: wangjianping@earth
 *Date:2012-06-26
 *BSD Licence
 */

#include <iostream>
#include <cstring>
#include <stdlib.h>
#include <stdint.h>

using namespace std;

typedef enum {add, del} operation;
class SkipNode{
    public:
        uint64_t val;
        unsigned opt:24;
        int level;
        string key;
        SkipNode **next;
        SkipNode(int level){
            next = new SkipNode *[level];
        }

};


class SkipList{
    private:
        int count;
        int size;
        int MaxLevel;
        SkipNode *entry;//The entry of the skplist
    public:
        SkipList(int size);
        bool SkipListInsert(string key, uint64_t val, operation opt);
        SkipNode *SkipNodeSearch(string data);
        //friend int main();

};

SkipList::SkipList(int size){
    size = size;//The maximum skipnode number
    count = 0;
    MaxLevel = 0;
    entry = new SkipNode(16);

    for(int i = 0; i <= 15; i++)
        entry->next[i] = entry;
}

bool SkipList::SkipListInsert(string key, uint64_t val, operation opt){
    SkipNode *temp[16];//Maximum level of skipnode
    SkipNode *x;
    int NewLevel;

    if(count == size)//skiplist is full
        return false;

    //locate the proper postion
    x = entry;
    for(int i = MaxLevel; i>=0; i--){
        while(x->next[i] != entry && x->next[i]->key < key)//look forward
            x = x->next[i];//jump
        temp[i] = x;
    }

    x = x->next[0];
    if(x != entry && x->key == key){//redundancy
        x->val = val;
        x->opt = opt;
        return false;
    }

    //Generate the new level
    for(NewLevel = 0; rand() < RAND_MAX/2 && NewLevel < 15; NewLevel++);
    //Set the upper level if necessary
    if(NewLevel > MaxLevel){
        for(int i = MaxLevel + 1; i <= NewLevel; i++)
            temp[i] = entry;//set the upper levels point to the entry
        MaxLevel = NewLevel;
    }

    //form the skipnode
    x = new SkipNode(NewLevel + 1);
    x->key = key;
    x->val = val;
    x->opt = opt;

    //Place all level pointers
    for(int i = 0; i <= NewLevel; i++){
        x->next[i] = temp[i]->next[i];
        temp[i]->next[i] = x;
    }

    count++;
    return true;
}


SkipNode *SkipList::SkipNodeSearch(string data){
    SkipNode *x = entry;
    //from the top level
    for(int i = MaxLevel; i >= 0; i--){
        while(x->next[i] != entry && x->next[i]->key < data)
            x = x->next[i];//move forward
    }
    x = x->next[0];
    if(x != entry && x->key == data)
        return x;
    return NULL;
}

int main(){
    SkipList sl(1000);
    sl.SkipListInsert("123",123,add);
    sl.SkipListInsert("234",234,del);
    sl.SkipListInsert("345",345,add);
    sl.SkipListInsert("456",456,add);

    for(SkipNode *it = sl.entry->next[0]; it != sl.entry; it = it->next[0])
        cout<<it->val<<endl;


    return 0;
}