How to get frequency of std:vectors in C++? - c++

Question

I have 5 vectors. I want to check how many times these vectors exist. I used the following code to compare if 2 vectors are equal, but now I have more than 2 vectors. I want to compare all these 5 vectors together and count how many times each vector exists.
How can I do it?
The output should be:
(0,0,1,2,3,0,0,0) = 2 time(s)
(0,0,1,2,3,4,0,0) = 1 time(s)
(0,0,2,4,3,0,0,0) = 1 time(s)
(0,0,6,2,3,5,6,0) = 1 time(s)
Here is my code:
#include <stdio.h>
#include <iostream>
#include <vector>
using namespace std;
void checkVec(vector<int> v){
vector<int> v0;
if(v0 == v){
cout << "Equal\n";
}
else{
cout << "Not Equal\n";
}
}
int main(){
vector<int> v1={0,0,1,2,3,0,0,0};
vector<int> v2={0,0,1,2,3,4,0,0};
vector<int> v3={0,0,2,4,3,0,0,0};
vector<int> v4={0,0,1,2,3,0,0,0};
vector<int> v5={0,0,6,2,3,5,6,0};
checkVec(v1);
return 0;
}

Answer 1

You can use std::map counting the number of occurences of each vector:
#include <map>
#include <vector>
#include <iostream>
using vec = std::vector<int>;
int main(){
vec v1={0,0,1,2,3,0,0,0};
vec v2={0,0,1,2,3,4,0,0};
vec v3={0,0,2,4,3,0,0,0};
vec v4={0,0,1,2,3,0,0,0};
vec v5={0,0,6,2,3,5,6,0};
std::map<vec,std::size_t> counter;
// Initializer list creates copies by default
// But you should not create vX variables anyway.
for(const auto& v: {v1,v2,v3,v4,v5}){
++counter[v];
}
std::cout<<"V1 is present " <<counter[v1]<<" times.\n";
return 0;
}
V1 is present 2 times.

Answer 2

Well, this is a contribution for Quimby answer, but if you know how many vectors you will get at compile time, use std::array to contain all that vector. If you know it at runtime instead, use std::vector as shown below
#include <map>
#include <vector>
#include <iostream>
#include <cstddef>
int main(){
std::vector<std::vector<int>> allVector
{
std::vector<int>{0,0,1,2,3,0,0,0},
std::vector<int>{0,0,1,2,3,4,0,0},
std::vector<int>{0,0,2,4,3,0,0,0},
std::vector<int>{0,0,1,2,3,0,0,0},
std::vector<int>{0,0,6,2,3,5,6,0},
};
std::map<std::vector<int>, std::size_t> counter;
for(const auto& v : allVector)
{
++counter[v];
}
// print out the array and it's frequency
for(const auto& pr : counter)
{
std::cout << '(';
for(std::size_t i {0}; i < pr.first.size(); ++i)
{
std::cout << pr.first[i];
if(i != pr.first.size() - 1)
std::cout << ' ';
}
std::cout << ") = " << pr.second << ", ";
}
return 0;
}