2024.2.5 作业

1.请编程实现哈希表的创建存储数组{12,24,234,234,23,234,23},输入key查找的值，实现查找功能

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include<math.h>
typedef int datatype;
typedef struct Node
{
	datatype data;
	struct Node *next;
}*node;
int prime(int m)
{
	for(int i=m;i>=2;i--)
	{
		int flag=0;
		for(int j=2;j<sqrt(m);j++)
		{
			if(i%j==0)
			{
				flag=-1;
				break;
			}
		}
		if(flag==0)
			return i;
	}
}
node create()
{
	node s=(node)malloc(sizeof(struct Node));
	if(s==NULL)
		return NULL;
	s->data=0;
	s->next=NULL;
	return s;
}
void insert_hash(int key,node hash[],int p)
{
	int index=key%p;
	node s=create();
	s->data=key;
	if(hash[index]==NULL)
		hash[index]=s;
	else
	{
		s->next=hash[index];
		hash[index]=s;
	}
}
void output(node hash[],int m)
{
	for(int i=0;i<m;i++)
	{
		printf("%d:",i);
		node p=hash[i];
		while(p)
		{
			printf("%-5d",p->data);
			p=p->next;
		}
		puts("");
	}
}
int search_key(node hash[],int p,int key)
{
	int index=key%p;
	node head=hash[index];
	while(head!=NULL)
	{
		
		if(key==head->data)
			return 0;
		head=head->next;
	}
	return -1;
}
int main(int argc, const char *argv[])
{
	int arr[]={12,24,234,234,23,234,23};
	int len=sizeof(arr)/sizeof(arr[0]);
	int m=len*4/3;//计算哈希表的长度
	node hash[m];//定义哈希表
	for(int i=0;i<m;i++)
		hash[i]=NULL;
	int p=prime(m);
	for(int i=0;i<len;i++)//把数组元素存到哈希表中
	{
		insert_hash(arr[i],hash,p);
	}
	//输出哈希表
	output(hash,m);
	//查找
	int key;
	printf("please enter the key:");
	scanf("%d",&key);
	int flag=search_key(hash,p,key);
	if(flag==0)
		puts("exist");
	if(flag==-1)
		puts("unexist");
	
	return 0;
}

2.现有数组{12,23,45,56,445,5676,6888],请输入key实现二分查找

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int half_search(int arr[],int key,int len,int low,int high)
{
	while(low<=high)
	{
		int m=(low+high)/2;
		if(key>arr[m])
		{
			low=m+1;
		}
		else if(key==arr[m])
		{
			return m;
		}
		else 
		{
			high=m-1;
		}
	}
	return -1;
}
int main(int argc, const char *argv[])
{
	int arr[]={12,23,45,56,445,5676,6888};
	int len=sizeof(arr)/sizeof(arr[0]);
	int low=1;
	int high=len;
	int key;
	printf("please enter the search key:");
	scanf("%d",&key);
	int index=half_search(arr,key,len,low,high);
	printf("the search index:%d\n",index);
	return 0;
}