078. Hashing (25)

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本文详细介绍了如何使用哈希表和二次探测算法进行数据插入操作，包括哈希函数的选择、二次探测的实现及质数表大小的优化策略。

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078. Hashing (25)
 
  
   
    时间限制
   
   
    100 ms
    

   
  
  
   
    内存限制
   
   
    65536 kB
    

   
  
  
   
    代码长度限制
   
   
    16000 B
    

   
  
  
   
    判题程序
   
   
    Standard
   
  
  
   作者
  
  
   CHEN, Yue
   

  
 
 
  The task of this problem is simple: insert a sequence of distinct positive integers into a hash table, and output the positions of the input numbers. The hash function is defined to be "H(key) = key % TSize" where TSize is the maximum size of the hash table. Quadratic probing (with positive increments only) is used to solve the collisions.
  Note that the table size is better to be prime. If the maximum size given by the user is not prime, you must re-define the table size to be the smallest prime number which is larger than the size given by the user.
  Input Specification:
  Each input file contains one test case. For each case, the first line contains two positive numbers: MSize (<=10⁴) and N (<=MSize) which are the user-defined table size and the number of input numbers, respectively. Then N distinct positive integers are given in the next line. All the numbers in a line are separated by a space.
  Output Specification:
  For each test case, print the corresponding positions (index starts from 0) of the input numbers in one line. All the numbers in a line are separated by a space, and there must be no extra space at the end of the line. In case it is impossible to insert the number, print "-" instead.
  Sample Input:
  4 4
10 6 4 15

  Sample Output:
  0 1 4 -

  提供Msize大小的哈希表（编号从0~Msize-1）  有N个要填入的值
  接着是N个要填入的值 key1  key2 ……
  首先找到一个质素，prime>=Msize;这个质素是最接近Msize的；令这个Msize=这个质素（只能被1和它本身整除的正整数）；
  hash    
     按照输入的key顺序，inner从0到Msize-1如果pos=（key+inner*inner）%Msize；
                                      一发现有table[pos]还没有放东西，就输出这个pos并置满；
                                      若都有放东西，就“-”
  评测结果
   时间 结果 得分 题目 语言 用时(ms) 内存(kB) 用户
8月17日
 00:19 答案正确 25 1078 C++
 (g++ 4.7.2) 21 384 datrilla
测试点
   测试点 结果 用时(ms) 内存(kB) 得分/满分
0 答案正确 1 180 12/12
1 答案正确 1 248 3/3
2 答案正确 1 308 5/5
3 答案正确 21 384 5/5

  
  #include<iostream>  
#include<vector> 
#include<math.h>
using namespace std;
int largerMsizeFirstPrime(int Msize)
{
  if (Msize <= 2)return 2;
  bool nofind=true;
  int i;
  while (nofind)
  {
    int eNd = sqrt(Msize); 
    for (i = 2; i <= eNd&&Msize%i != 0; i++)
      ;
    if (i> eNd)nofind = false;
    else Msize++;

  }
  return Msize;
}
int main()
{
  int N,Msize,data,pos,index;  
  cin >> Msize >>N; 
  Msize = largerMsizeFirstPrime(Msize);
  vector<bool>table(Msize, true); 
  for (index = 0; index < N;index++)
  {
        cin >> data;   
      int inner = 0;
      do
      {
        pos = (data + inner*inner) % Msize;
        inner++;
      } while (!table[pos] && inner < Msize);
      if (inner== Msize)
      {
        if (index>0)cout << " ";
        cout <<"-";
      }
      else
      { 
        table[pos] = false;
        if (index>0)cout << " ";
        cout << pos;
      }  
  }
  cout << endl;
    system("pause");
  return 0;
}