89.hash算法实现CSDN密码处理

• 初始化,数据的行数,hash链表结构体,存储头结点

   #define _CRT_SECURE_NO_WARNINGS
   #include <stdio.h>
   #include <stdlib.h>
   char path[] = "csdn.txt";
   //数据的行数
   #define N 6428633
   //字符串hash算法
   unsigned int BKDRHash(char *str);
  
   //hash链表结构体(结构体)
   struct   beitai
   {
       char *pstr;//存储字符串
       struct   beitai *pNext;//下一个节点
   };
  
   //头结点
   struct info
   {
       struct   beitai *pbt;
   };
  
   //保持所有头结点
   struct info *pall = NULL;

• 字符串hash算法

   //hasn算法
   unsigned int BKDRHash(char *str)
   {
       //和数据对应的位数有关
       unsigned int seed = ; // 31 131 1313 13131 131313 etc..
       unsigned int hash = ;
  
       while (*str)
       {
           hash = hash * seed + (*str++);
       }
  
       return (hash & 0x7FFFFFFF);
   }

• 实现读取一行的数据的修改,并对这个字符串进行hash算法

   void changestr(char *str)
   {
       //备份地址
       char *pbak = str;
       //去除空格
       //下标
       int i = ;
       //游标
       int j = ;
       while ((str[i] = str[j++]) != '\0')
       {
           if (str[i] != ' ')
           {
               i++;
           }
       }
       //截断
       char *p1 = strstr(pbak, "#");
       if (p1 != NULL)
       {
           *p1 = '\0';
       }
   }

• 载入内存

   void init()
   {
  
       pall = malloc(N*sizeof(struct info));
       memset(pall, , N*sizeof(struct info));//清空
  
       //打开文件
       FILE *pf = fopen(path, "r");
       for (int i = ; i < N; i++)
       {
           char str[] = {  };
           char strbak[] = {  };
           //读取一行
           fgets(str, , pf);
           //拷贝
           strcpy(strbak, str);
           //字符串处理
           changestr(str);
           //获取hash对应的数字
           unsigned int  data = BKDRHash(str);
           //进行取余
           unsigned int id = data %N;
           pall[id].pbt = addstr(pall[id].pbt, strbak);//找到链表节点，插入
       }
       fclose(pf);
   }

• 插入节点

   //插入
   struct   beitai *addstr(struct   beitai *phead, char *str)
   {
       //开辟节点
       struct   beitai *pnew = calloc(, sizeof(struct   beitai));
       //获取字符串长度并开辟内存
       int length = strlen(str);
       pnew->pstr = calloc(length + , sizeof(char));
       //拷贝
       strcpy(pnew->pstr, str);
       //下一个结点为NULL
       pnew->pNext = NULL;
       //如果头结点为空
       if (phead==NULL)
       {
           phead = pnew;
       }
       //否则头部插入
       else
       {
           pnew->pNext = phead;
           phead = pnew;
  
       }
       return phead;
   }

• 实现查询

   //实现查询
   void find(struct   beitai *phead, char *findstr)
   {
       while (phead!=NULL)
       {
           char*ps = strstr(phead->pstr, findstr);
           if (ps!=NULL)
           {
               printf("%s", phead->pstr);//查找
           }
           phead = phead->pNext;
       }
   }

• 获取有多少行

   int getN()
   {
       FILE *pf = fopen(path, "r");
       if (pf == NULL)
       {
           return -;
       }
       else
       {
           int i = ;
           while (!feof(pf))
           {
               char str[] = {  };
               fgets(str, , pf);//读取
               i++;
           }
           fclose(pf);
           return i;
       }
   }

• 主函数

   //主函数
   void main()
   {
       //初始化并载入内存
       init();
       //查询
       while ()
       {
           char str[] = {  };
           scanf("%s", str);
           unsigned int id = BKDRHash(str) % N;
           find(pall[id].pbt, str);
       }
       system("pause");
   }