C语言实现HashMap
   在做算法题时,需要使用到HashMap提高效率，虽然高级语言中大豆实现了这种数据结构，但是高级语言的效率低，于是打算自己实现HashMap，加深理解，使用C语言实现了HashMap的创建（CreateHashMap）、取<k,v>对（Get）、插入<k,v>对（Put）输出（PrintHashMap）以及销毁（DestoryHashMap）,具体程序如下：
1.类型定义如下：
    typedef struct{
        int key;
        int val;
    }DataType;
    typedef struct{
        DataType data;
        struct HashNode *next;
    }HashNode;
    typedef struct{
        int size;
        HashNode *table;
    }HashMap,*hashmap;

2.CreateHashMap
    //f1_createHashMap
    HashMap *CreateHashMap(int *nums,int size){
        HashMap *hashmap=(HashMap*)malloc(sizeof(HashMap));
        hashmap->size=2*size;
        hashmap->table=(HashNode *)malloc(sizeof(HashNode)*hashmap->size);
        int j=0;
        for(j=0;j<hashmap->size;j++){
            hashmap->table[j].data.val=INT_MIN;
            hashmap->table[j].next=NULL;
        }
        int i=0;
        while(i<size){
            int pos=abs(nums[i])%hashmap->size;
            if(hashmap->table[pos].data.val==INT_MIN){
                hashmap->table[pos].data.key=i;
                hashmap->table[pos].data.val=nums[i];
            }
            else{
                HashNode *lnode=(HashNode*)malloc(sizeof(HashNode)),*hashnode;
                lnode->data.key=i;
                lnode->data.val=nums[i];
                lnode->next=NULL;
                hashnode=&(hashmap->table[pos]);
                while(hashnode->next!=NULL){
                    hashnode=hashnode->next;
                }
                hashnode->next=lnode;
            }
            i++;     
        }
        return hashmap;
    }
  对于hashmap->size=2*size; hashmap中table的长度为什么是给定数组长度的2倍？这涉及到hash表的冲突因子，也可以选取别的数值；详细可以参考严蔚敏《数据结构》中的相关章节；
3.GetKeyValue
    //f3_GetHashNode
    int Get(int value,HashMap hashmap){
        int pos=abs(value)%hashmap.size;
        HashNode *pointer=&(hashmap.table[pos]);
        while(pointer!=NULL){
                if(pointer->data.val==value)
                    return pointer->data.key;
                else
                    pointer=pointer->next;
                    
            }
         
        return -1;
    }
4.PutKeyValue
    //f4_Put
    int Put(int key,int value,HashMap hashmap){
         int pos=abs(value)%hashmap.size;
         HashNode *pointer=&(hashmap.table[pos]);
         if(pointer->data.val==INT_MIN)
            {
             pointer->data.val=value;
             pointer->data.key=key;
            }
        else{
            while(pointer->next!=NULL)
                 pointer=pointer->next;
            HashNode *hnode=(HashNode *)malloc(sizeof(HashNode));
            hnode->data.key=key;
            hnode->data.val=value;
            hnode->next=NULL;
            pointer->next=hnode;
       }
       return 1;
    }   
5.PrintHashMap
    //f2_PrintHashMap
    void PrintHashMap(HashMap* hashmap){
        printf("%===========PrintHashMap==========\n");
        int i=0;
        HashNode *pointer;
        while(i<hashmap->size){
            pointer=&(hashmap->table[i]);
            while(pointer!=NULL){
                if(pointer->data.val!=INT_MIN)
                  printf("%10d",pointer->data.val);
                else
                  printf("        [ ]");
                pointer=pointer->next;
            }
            printf("\n---------------------------------");
            i++;
            printf("\n");
        }
        printf("===============End===============\n");
    }
6.DestoryHashMap
    //f5_DestoryHashMap
    void DestoryHashMap(HashMap *hashmap){
        int i=0;
        HashNode *hpointer;
        while(i<hashmap->size){
            hpointer=hashmap->table[i].next;
            while(hpointer!=NULL){
               
                hashmap->table[i].next=hpointer->next;
                free(hpointer);
                hpointer=hashmap->table[i].next;
                }
            i++;
        }
        free(hashmap->table);
        free(hashmap);
        printf("Destory hashmap Success!");
    }