#include<stdio.h> #include<stdlib.h> #include<string.h> #define N 30 typedef char elemtype[19]; typedef struct node { elemtype name; int num; }tablenode;/*定义结点类型*/ tablenode *L;    void create_hash()/*伪随机法构造哈希表*/     {       int i,sum;       char string[19];       L=(tablenode *)malloc(N*sizeof(tablenode));       if(!L)       {        printf("\noverflow!");        exit(0);       }      for(i=0;i<N;i++)      {       L[i].name[0] ='\0';       L[i].num=i;       }     for(i=0;i<N;i++)     {     printf("\nplease input the name of the %dth student:",i+1);     gets(string);     sum=jisuan(string);     if(insert_hash(sum,string))     printf("\ninsert node succeed!");         } } int suiji()/*产生随机数*/ { int di; randomize(); di=random(2*N); di=(N-di-1)%N; return di; } int insert_hash(int result,char *q)/*向哈希表中插入结点*/ {   int num,flag=0;   num=result%N;   if(L[num].name[0]=='')    {    strcpy(L[num].name,q);    flag=1;    return flag;    }   else    {     result=result+suiji();     insert_hash(result,q);    } } int hash_search(int x,char *s) { int i; i=x%N; if(strcmp(L[i].name,s)==0) { printf("\n find it at the %dth location!",i+1); return 1; } else { x=x+suiji(); hash_search(x,s); return 0; } } int jisuan(char *p)/*计算字符串的值*/ { int sum=0,di; for(;*p!='\0';p++) sum+=*p; return sum; } void search(void)/*伪随机法哈希表的查找*/ { elemtype new; int sum; printf("\nplease input the name of the student search:"); scanf("%s",new); sum=jisuan(new); if(!hash_search(sum,new)) { printf("\nnot exit the student!!!!"); getch(); return; } } main() { clrscr(); create_hash(); search(); } 

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