C++ (SPOJ - POL-polowa) - problem with compilation - c++

Question

I have problem with making correct code for this task in SPOJ https://pl.spoj.com/problems/POL/.
When I wrote all what I needed, program worked correctly. But when I tried to convert it in function, I have on ideone.com problem like this -> double free or corruption (out). Can anybody help me please ? What I am doing wrong ? I am beginner and I realize that can be very trivial.
#include <iostream>
using namespace std;
int polowa()
{
int t;
cin>>t;
string slowa[100]={};
string nowe_slowa[100]={};
for (int i=0;i<t;i++)
{
cin>>slowa[i];
}
for (int i=0;i<t;i++)
{
int k=slowa[i].length()/2;
nowe_slowa[i]=slowa[i].substr(0,k);
cout<<nowe_slowa[i]<<endl;
}
}
int main()
{
polowa();
return 0;
}

Answer 1

int polowa() promises to return an int, but the return keyword is conspicuously absent from the function.
Looking over the code, you never use more than one element at a time. Odds are good you could rewrite this function to use no arrays and only one loop. – user4581301
You don't have to separate reading input and print output. Arrays are not needed. Proposed implementation:
#include <iostream>
#include <string>
int main()
{
unsigned tests;
std::cin >> tests;
while (tests--)
{
std::string word;
std::cin >> word;
std::cout << word.substr(0, word.length() / 2) << "\n";
}
}

Answer 2

According to Dessus proposition I wanted to make this code as a function called in int main(). But SPOJ can't accept me this code (when i am compiling this in code blocks, everythings okay).
#include <iostream>
#include <string>
std::string nowe_slowo(int t)
{
while (t--)
{
std::string word;
std::cin >> word;
std::cout<<word.substr(0, word.length() / 2)<<"\n";
}
}
int main()
{
unsigned tests;
std::cin >> tests;
nowe_slowo(tests);
}