#include <functional>
#include <iostream>
#include <map>
 
using namespace std;
 
function<int(int)> memoize(function<int(int)> func)
{
    map<int, int> results;
 
    function<int(int)> memoized([&] (int i) {
 
        if(results.count(i)) {
            return results[i];
        } else {
            int result = func(i);
            results.insert(pair<int, int>(i, result));
            return result;
        }
 
    });
 
    return memoized;
}
 
int fib(int i)
{
    if (i == 0 || i == 1) {
        return i;
    } else {
        return fib(i - 1) + fib(i - 2);
    }
}
 
int main()
{
    auto fibm = memoize(&fib);
    cout << fibm(23) << endl;
 
    cin.get();
}

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