Why am I getting the error with max function when I use long long int and int as arguments

Question

I'am new to C++ just had this unexpected error with using max function, where I pass arguments of type long long and int

When i pass (int,int) as arguments or (long long,long long) it works fine but not with (long long,int)

ll painter(int board[],int n,int k)
{

 ll  s = 0,total_min;
 ll ans;

 for(ll i = 0;i < n;i++)
   { total_min += board[i];
       s = max(s,board[i]);

}

This is the error showing

prog.cpp:39:25: error: no matching function for call to 'max(int&, long long int&)
        s =max(s,board[i]);"

Answer 1

Because std::max is a function template whose signature is, for example,

template< class T > 
const T& max( const T& a, const T& b );

complete list at: https://en.cppreference.com/w/cpp/algorithm/max

Now, when instantiating the template you give two different types but the templates only wants one. You have to explicitly specify the template argument, like in this example:

#include <algorithm>

int main(){
    int a{5};
    long long int b{55};
    return std::max<long long int>(a, b);
}   

As noted in the comments (user John), you can also cast one of the two, for example you can cast the int to long long