如何获取哈希表的最大链的长度？

Question

I have a hash table program shown below

#include<bits/stdc++.h> 
#include <algorithm>
std::string fileName;
std::fstream readFile;
const int arraySize = 100;
int storeFile[arraySize]; 

class Hash 
{ 
    std::list<int> *table; 
    std::list<int>::iterator anItetator;
public:  
    int count = 0;
    int mod = 100; 
    Hash();
    Hash(int Value);  

    void insertItem(int key); 

    int hashFunction(int key) { 
        return (key % mod); 
    } 
  
    void loopHash(); 

    void displayHash(); 
};

Hash::Hash(){

} 

Hash::Hash(int b) 
{ 
    this->mod = b; 
    table = new std::list<int>[mod]; 
} 
  
void Hash::insertItem(int key) 
{ 
    int index = hashFunction(key); 
    table[index].push_back(key);  
} 

void Hash::displayHash() { 
  for (int i = 0; i < mod; i++) { 
    std::cout << i; 
    for (auto x : table[i]) 
      std::cout << " --> " << x; 
    std::cout << std::endl; 
  } 
}

void Hash::loopHash() {

for(anItetator = table->begin(); anItetator != table->end(); ++anItetator){

   if(table->empty()==true) {
    count++;
    }

   std::cout << "Total number of empty entries is: " << count;
   std::cout << "The largest chain is: "  << *std::max_element(table->begin(),table->end());
}

}

int main(int argc, char *argv[])
{
     int n = arraySize;

     Hash h(h.mod); 

     std::cout << "Please enter the name of the file: " << std::endl;
     std::cin >> argv[0];                                            

     fileName = argv[0];

     std::cout << "Attempting to read file " << fileName << std::endl;

     readFile.open(fileName); 

for(int i = 0; i < n; i++) {
 
     while (readFile >> storeFile[i])
     {
        h.insertItem(storeFile[i]); 
     }
}
     //h.displayHash();     
     h.loopHash();
     readFile.close();
     return 0;
}

However theres specific information i need from the results that im not quite sure how to find. These are 2 outputs

1. The number of empty elements in the hash table
2. The length of the longest chain

Ive attempted to do something like this with my void Hash::loopHash() however this function prints no values.

If anyone knows about hash-tables and can help me with this that would be great.

Answer 1

for(anItetator = table->begin(); anItetator != table->end(); ++anItetator){ iterates over the elements in the first std::list , because table is a pointer to a list<> (but that list is expected to the first of mod such lists effectively forming an array of list s).

What you should do to inspect each bucket in the hash table is access table as an array, using the array length you know you called new with to allocate the memory; eg

int num_empty_buckets = 0;
int longest_chain = 0;
for (int index = 0; index < mod; ++index) {
    if (table[index].empty())
        ++num_empty_buckets;
    longest_chain = std::max(table[index].size(), longest_chain);
}
// print 'em...