DS Bonus 2: QQ Account Management-优快云博客

本文介绍了一种处理大量用户登录和注册请求的方法，通过哈希表和AVL树两种数据结构来高效管理QQ账号信息，确保登录和注册操作的快速响应。

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题目要求

You are supposed to implement the functions of account"Log in" and "Register" for the most popular instantmessager QQ. The most challenging partis that QQ now has more than a billion users.

Input Specification:

Each input file contains one test case. For each case, the first line contains aninteger N (£10⁵) - the total number ofqueries. Then N lines follow, each contains a query in the format:

Command QQ_No Password

where "Command" is either"R" (meaning to register a new account, and hence followed by a newaccount number and a password), or "L" (meaning to log in with anexisting account, and hence followed by the account number and the password);"QQ_No" is an integer that is greater than 1000 and no more than 10digits long; and "Password" is a string with no less than 6 and nomore than 16 characters without any space.

Output Specification:

For each test case, print the correspondingmessage for each query in a line. Themessages are:

l If a new account is successfullyregistered, output "Register Successful";

l If the new registering account numberalready exists, output "ERROR: Account Number Already Exists";

l If log in successfully, output "Log inSuccessful";

l If the log in account does not exist, output"ERROR: Account Not Exist";

l If log in with a wrong password, output"ERROR: Wrong Password".

Sample Input:

L 1234567890 myQQ@qq.com

R 1234567890 myQQ@qq.com

L 1234567890 myQQ@qq

L 1234567890 myQQ@qq.com

Sample Output:

ERROR: Account Not Exist

ERROR: Account Number Already Exists

ERROR: Wrong Password

哈希法

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MinTableSize 5
typedef struct QQ* Database; 
typedef struct HashEntry Cell;
typedef struct HashT *HashTable;
struct QQ{
	char id[15];
	char password[20];
};
enum KindOfEntry{Legitimate,Empty,Deleted};

struct HashEntry{
	struct QQ user;
	enum KindOfEntry Info;
};

struct HashT{
	int tablesize;
	Cell *thecells;
};
int Isprime(int n){
	int i;
	if(n == 1)
		return 0;
	for(i = 2;i*i<=n;i++)
		if(n %i == 0)
			break;
	if(i*i<=n)
		return 0;
	else return 1;
}
int nextprime(int n){
	while(!Isprime(n)){
		n++;
	}
	return n;
}

int Hash(const char *key,int n){
	int hashval;
	hashval = 0;
	while(*key != '\0'){
		hashval = (hashval << 1) + *key++;
	}
	return hashval % n;
}
HashTable Initialize(int tablesize){
	HashTable h;
	int i;
	if(tablesize<MinTableSize){
		perror("Table size too small\n");
		return NULL;
	}
	h = (HashTable)malloc(sizeof(struct HashT));
	if(h == NULL){
		perror("Out of Space\n");
		return NULL;
	}
	h->tablesize = nextprime(tablesize);
	h->thecells = (Cell*)malloc(sizeof(Cell)*h->tablesize);
	if(h->thecells == NULL){
		perror("Out of Space\n");
		return NULL;
	}
	for(i = 0;i<h->tablesize;i++)
		h->thecells[i].Info = Empty;
		return h;
}
int Find(char *key,HashTable h){
	int currentpos;
	int collisionnum;
	collisionnum = 0;
	currentpos = Hash(key,h->tablesize);
	while(h->thecells[currentpos].Info != Empty&&strcmp(h->thecells[currentpos].user.id,key)){
		currentpos += 2*++collisionnum-1;
		if(currentpos>=h->tablesize)
			currentpos -= h->tablesize;
	}
	return currentpos;
}

void Insert(struct QQ key,HashTable h){
	int pos;
	pos = Find(key.id,h);
	if(h->thecells[pos].Info!=Legitimate){
		h->thecells[pos].Info = Legitimate;
		h->thecells[pos].user = key;
	}
}
struct QQ *findcount(HashTable h,char *count){
	int pos;
	pos = Find(count,h);
	if(h->thecells[pos].Info == Empty)
		return NULL;
	else return &h->thecells[pos].user;
}
void CountInsert(HashTable h,char *count,char *pwd){
	struct QQ user;
	strcpy(user.id,count);
	strcpy(user.password,pwd);
	Insert(user,h);
}
HashTable ReHash(HashTable h){
	Cell *oldcells;
	int oldsize,i;
	oldcells = h->thecells;
	oldsize = h->tablesize;
	h = Initialize(oldsize*2);
	for(i = 0;i<oldsize;i++)
		if(oldcells[i].Info == Legitimate)
			Insert(oldcells[i].user,h);
		free(oldcells);
		return h;
}
int main(){
	Database r,d,p;
	int n,size;
	HashTable h;
	char cmd,count[15],pwd[20],*s;
	scanf("%d",&n);
	getchar();
	r = NULL;
	size = 0;
	h = Initialize(100000);
	while(n--){
		scanf("%c%s%s",&cmd,&count,&pwd);
		getchar();
		d = findcount(h,count);
		if(cmd == 'L'){
			if(d == NULL)
				printf("ERROR: Account Not Exist\n");
			else if(strcmp(d->password,pwd))
			       printf("ERROR: Wrong Password\n"); 
			else printf("Log in Successful\n");	
	    } 
	    else if(cmd == 'R') {
	    	if(d != NULL)
	    		printf("ERROR: Account Number Already Exists\n");
	    	else{
	    		printf("Register Successful\n");
	    	  	CountInsert(h,count,pwd);
	    	  	size++;
	    	  	//if(size == h->tablesize/2)
	    	  		//h = ReHash(h);
	    	}
	    }
	}
	return 0;
}

AVL TREE

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
typedef struct QQ* Database; 
struct QQ{
	char id[15];
	char password[20];
	int height;
	Database left,right;
};
//Tree search
Database findcount(Database d,char *id){
	while(d != NULL){
	if(strcmp(id,d->id) == 0) break;
	else if(strcmp(id,d->id)<0) d = d->left;
	else if(strcmp(id,d->id)>0) d = d->right;
    }
    return d;
}

//AVL tree
int height(Database r){
	if(r == NULL)
		return -1;
	else return r->height;
}
Database SingleRotateWithLeft(Database p){
	Database q;
	q = p->left;
	p->left  = q->right;
	q->right = p;
	p->height = height(p->left)>height(p->right)?height(p->left) + 1:height(p->right) + 1;
	q->height = height(q->left)>height(q->right)?height(q->left) + 1:height(q->right) + 1;
	return q;
}
Database SingleRotateWithRight(Database p){
	Database q;
	q = p->right;
	p->right  = q->left;
	q->left = p;
	p->height = height(p->left)>height(p->right)?height(p->left) + 1:height(p->right) + 1;
	q->height = height(q->left)>height(q->right)?height(q->left) + 1:height(q->right) + 1;
	return q;
}
Database DoubleRotateWithLeft(Database p){
	p->left = SingleRotateWithRight(p->left);
	return SingleRotateWithLeft(p);
}
Database DoubleRotateWithRight(Database p){
	p->right = SingleRotateWithLeft(p->right);
	return SingleRotateWithRight(p);
}
Database treeinsert(Database r,char *id,char *pwd){
	Database p;
	if(r == NULL){
		r = (Database)malloc(sizeof(struct QQ));
		if(r == NULL){
			printf("Out of Space\n");
			return NULL;
		}
		strcpy(r->id,id);
		strcpy(r->password,pwd);  
        r->left = r->right = NULL;
        r->height = 0;  
	}
	else if(strcmp(id,r->id)<0){
		r->left = treeinsert(r->left,id,pwd);
		if(height(r->left) - height(r->right) == 2)
			if(strcmp(id,r->left->id)<0)
				r = SingleRotateWithLeft(r);
			else r = DoubleRotateWithLeft(r);
	}
	else if(strcmp(id,r->id)>0){
		r->right = treeinsert(r->right,id,pwd);
		if(height(r->right) - height(r->left) == 2)
			if(strcmp(id,r->right->id)>0)
				r = SingleRotateWithRight(r);
			else r = DoubleRotateWithRight(r);
		}
	r->height = height(r->left)>height(r->right)?height(r->left)+1:height(r->right)+1;
	return r;
	}

int main(){
	Database r,d,p;
	int n;
	char cmd,count[15],pwd[20],*s;
	scanf("%d",&n);
	getchar();
	r = NULL;
	while(n--){
		scanf("%c%s%s",&cmd,&count,&pwd);
		getchar();
		d = findcount(r,count);
		if(cmd == 'L'){
			if(d == NULL)
				printf("ERROR: Account Not Exist\n");
			else if(strcmp(d->password,pwd))
			       printf("ERROR: Wrong Password\n"); 
			else printf("Log in Successful\n");	
	    } 
	    else if(cmd == 'R') {
	    	if(d != NULL)
	    		printf("ERROR: Account Number Already Exists\n");
	    	else{
	    		printf("Register Successful\n");
	    	    r = treeinsert(r,count,pwd);
	    	}
	    }
	}
	return 0;
}