Is there a way to keep a resource intensive C++ code running?

  ackermann, c++, recursion

I am trying to run the Ackermann function1 and I am having an issue. I am trying to run the program through my Command Prompt, on a Windows 10 machine, and a few seconds after reaching the value pair (4,0) the program stops. I am assuming because it has run out of available resources, but I am not sure at all. Is there a way to fix this issue? TIA.

Here is the code in question as well.

#include <iostream>
#include <ctime>

int ack(int m, int n)
{
    int ans;
    if (m == 0)
        ans = n + 1;

    else if (n == 0)
        ans = ack(m - 1, 1);

    else
        ans = ack(m - 1, ack(m, n - 1));

    return ans;
}

void runAck(time_t start) 
{
    int answer;
    double seconds;
    time_t now_t;

    for(int i = 0; i <= 6; i++)
    {
        for(int j = 0; j<= 6; j++)
        {
            answer = ack(i, j);
            time(&now_t);
            seconds = difftime(now_t, start);
            printf("Ackermann(%i, %i) is %i. Found in %.3f seconds.n", i, j, answer, seconds);
        }
    }
}

int main()
{
    std::cout << "Testing of the Ackermann recursion." << std::endl;
    time_t start = time(NULL);
    runAck(start);
    
    return 0;
}

I initially thought it was because I was using VSCode to access the command prompt but when I use it directly there is no change. While writing this question, I just thought of trying out a different OS or Ubuntu to see if there is any difference.

My goal is just to get to (4,1) to see how much faster it is now to calculate.

1 The Ackermann Function is a recursion function that was developed as computer theory to create a function that can only be calculated recursively.

Source: Windows Questions C++

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