no matching function for call to ‘Kt::Kt(int&, int)’ - c++

Question

my error: no matching function for call to ‘Kt::Kt(int&, int)’
I can't figure out what is causing this error. It occurs in the first function where all the getline calls are. The compiler is specifically calling out the third, fifth, and last one, but I'm pretty sure there is something wrong with all of them.
main.cpp
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
struct Kt
{
int key = -1;
int count = 0;
};
int kthBiggestFrequency(std::vector<int> a, int k)
{
vector<Kt> *arr = new vector<Kt>;
for (auto &&item : a)
{
if (arr -> empty())
{
arr -> emplace_back(item, 1);
}
else
{
for (auto &&i : *arr)
{
if (item == i.key)
{
i.count++;
}
else
{
arr -> push_back({item, 1});
}
}
}
}
return 1;
}
int main()
{
vector<int> arr{1,1,1,3,2,3,2,4,4,4,1};
int k = 1;
kthBiggestFrequency(arr, k);
}
I need support. I don't know how i can fix it.
my output
[main.cpp 2020-03-14 10:06:15.338]
,,In file included from /usr/include/x86_64-linux-gnu/c++/7/bits/c++allocator.h:33:0,
from /usr/include/c++/7/bits/allocator.h:46,
from /usr/include/c++/7/string:41,
from /usr/include/c++/7/bits/locale_classes.h:40,
from /usr/include/c++/7/bits/ios_base.h:41,
from /usr/include/c++/7/ios:42,
from /usr/include/c++/7/ostream:38,
from /usr/include/c++/7/iostream:39,
from main.cpp:1:
/usr/include/c++/7/ext/new_allocator.h: In instantiation of ‘void
__gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = Kt; _Args = {int&,
int}; _Tp = Kt]’:
/usr/include/c++/7/bits/alloc_traits.h:475:4: required from ‘static void
std::allocator_traits<std::allocator<_CharT>
>::construct(std::allocator_traits<std::allocator<_CharT> >::allocator_type&, _Up*, _Args&&
...) [with _Up = Kt; _Args = {int&, int}; _Tp = Kt;
std::allocator_traits<std::allocator<_CharT> >::allocator_type = std::allocator<Kt>]’
/usr/include/c++/7/bits/vector.tcc:100:30: required from ‘void std::vector<_Tp,
_Alloc>::emplace_back(_Args&& ...) [with _Args = {int&, int}; _Tp = Kt; _Alloc =
std::allocator<Kt>]’
main.cpp:30:40: required from here
/usr/include/c++/7/ext/new_allocator.h:136:4: error: no matching function for call to
‘Kt::Kt(int&, int)’
{ ::new((void *)__p) _Up(std::forward<_Args>(__args)...); }
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
main.cpp:8:8: note: candidate: constexpr Kt::Kt()
struct Kt
^~
main.cpp:8:8: note: candidate expects 0 arguments, 2 provided
main.cpp:8:8: note: candidate: constexpr Kt::Kt(const Kt&)
main.cpp:8:8: note: candidate expects 1 argument, 2 provided
main.cpp:8:8: note: candidate: constexpr Kt::Kt(Kt&&)
main.cpp:8:8: note: candidate expects 1 argument, 2 provided
how to fix it?

Answer 1

The line arr->emplace_back(item, 1); tries to access the constructor Kt::Kt(int&, int) and fails because this constructor doesn't exists. You can fix it by creating this constructor or by using push_back instead of emplace_back.
To create this constructor:
struct Kt {
int key = -1;
int count = 0;
Kt(int &k, int c) : key(k), count(c) {}
//Kt(int k, int c) : key(k), count(c) {} // Will work too
};
To use push_back:
arr->push_back({item, 1});
One more thing, don't forget to release the allocation of the vector inside the function, and in general try to avoid dynamic allocations (or do it with smart pointers to avoid such mistakes).