C++ long compilation time of const array

Question

I'm making a game in Node.js with a C++ component. This C++ component is invoked often (as a subprocess) and is a bottleneck. Thus, I hardcoded its assets as const arrays to make it run faster.

However, I noticed that my C++ code takes a long time to compile. Following is a demonstration of the problem:

#include <iostream>
#include <vector>
#define d 3,
#define _ 999,
// an array holding some game assets
const std::vector<std::vector<std::vector<int>>> STRUCTURES {

    { // you should make 80 copies of this paragraph before benchmarking
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
    },

};
int main(int argc, char **argv){
    // prevent optimizer from ignoring the big array
    std::cout << STRUCTURES.size() << std::endl;
    return 0;
}

If you repeat the middle paragraph 80 times, it'll be comparable in size to my C++ program. I compile with g++ test.cpp -O3 and it takes 36 seconds to compile. I don't understand why this is so slow. Is there something I can change to make it compile much faster?

Answer 1

The solution, as suggested by Barmar and Sam Varshavchik, is to avoid std::vector.

There are too many vectors and the optimizer is taking a lot of time to deal with that. std::array can be used instead. For this sample, that means:

#include <iostream>
#include <vector>
#include <array>
#define d 3,
#define _ 999,
// an array holding some game assets
const std::vector<std::array<std::array<int,37>,37>> STRUCTURES {

    {{ // you should make 80 copies of this paragraph before benchmarking
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ d d d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ d d d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ d d d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ d d d d d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ d d d d d d d _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
        { _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ },
    }},

};
int main(int argc, char **argv){
    // prevent optimizer from ignoring the big array
    std::cout << STRUCTURES.size() << std::endl;
    return 0;
}

Notice that I still used a single std::vector for the outermost dimension. This does not present a significant overhead when compiling.

Answer 2

Not using dynamic allocation helps:

template <typename T, int a, int b, int c>
using sprites = std::array<std::array<std::array<T, c>, b>, a>;

But not allocating at all must be faster. Now I don't know about you, but I find getting the initializers correct and lined up Very Tedious(TM) so, let's not:

// an array holding some game assets
static constexpr char STRUCTURES[] {
    // pos 0
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_________________________ddddddd_____"
    "______________________ddddddddddd____"
    "_____________________ddddddddddddd___"
    "____________________dddddddddddddd___"
    "___________________ddddddddddddddd___"
    "__________________dddddddddddddddd___"
    "_________________dddddddddddddddd____"
    "________________ddddddddddddddddd____"
    "_______________ddddddddddddddddd_____"
    "______________ddddddddddddddddd______"
    "____________dddddddddddddddddd_______"
    "___________dddddddddddddddddd________"
    "__________ddddddddddddddddddd________"
    "_________ddddddddddddddddddd_________"
    "________ddddddddddddddddddd__________"
    "________ddddddddddddddddddd__________"
    "_______dddddddddddddddddddd__________"
    "______dddddddddddddddddddd___________"
    "______dddddddddddddddddddd___________"
    "______dddddddddddddddddddd___________"
    "______ddddddddddddddddddd____________"
    "______ddddddddddddddddddd____________"
    "______dddddddddddddddddd_____________"
    "______ddddddddddddddddd______________"
    "_______ddddddddddddddd_______________"
    "________ddddddddddddd________________"
    "_________ddddddddddd_________________"
    "___________ddddddd___________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    // pos 1
    // ....
    // ....
    // ....
    "_____________________________________"
    "_____________________________________"
    // pos 81
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_________________________ddddddd_____"
    "______________________ddddddddddd____"
    "_____________________ddddddddddddd___"
    "____________________dddddddddddddd___"
    "___________________ddddddddddddddd___"
    "__________________dddddddddddddddd___"
    "_________________dddddddddddddddd____"
    "________________ddddddddddddddddd____"
    "_______________ddddddddddddddddd_____"
    "______________ddddddddddddddddd______"
    "____________dddddddddddddddddd_______"
    "___________dddddddddddddddddd________"
    "__________ddddddddddddddddddd________"
    "_________ddddddddddddddddddd_________"
    "________ddddddddddddddddddd__________"
    "________ddddddddddddddddddd__________"
    "_______dddddddddddddddddddd__________"
    "______dddddddddddddddddddd___________"
    "______dddddddddddddddddddd___________"
    "______dddddddddddddddddddd___________"
    "______ddddddddddddddddddd____________"
    "______ddddddddddddddddddd____________"
    "______dddddddddddddddddd_____________"
    "______ddddddddddddddddd______________"
    "_______ddddddddddddddd_______________"
    "________ddddddddddddd________________"
    "_________ddddddddddd_________________"
    "___________ddddddd___________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
    "_____________________________________"
};

Naive Indexing Helper

Now, of course, you wanted ints and mapped the chars to certain values (like 3 and 999 in this case). To get that, we can use a naive indexing helper:

struct Helper {
    constexpr int operator()(int a, int b, int c) const {
        switch (auto ch = STRUCTURES[a*37*37 + b*37 + c]) {
            case 'd': return 999;
            case '_': return 3;
        }
        return 0;
    }
};

Now we can write main to print a randomm "glyph", "sprite" or whatever those resources are:

#include <iostream>
#include <iomanip>

int main() {
    auto a = rand() % 81;

    Helper index;
    for (int b = 0; b < 37; ++b) {
        for (int c = 0; c < 37; ++c)
            std::cout << std::setw(4) << index(a, b, c);
        std::cout << "\n";
    }
}

It prints (I had 81x the same "image"):

   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3 999 999 999 999 999 999 999   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3
   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3   3

Non-Naive Indexing Helper: Boost MultiArray

Much less code, much more features. Now you can use .size() and ranged-for:

#include <boost/multi_array.hpp>

int main() {
    constexpr std::array shape {81,37,37};
    boost::const_multi_array_ref<char, 3> view(STRUCTURES, shape);

    auto const& sprite = view[rand() % view.size()];
    for (auto const& row : sprite) {
        for (auto const& cell : row)
            printf("%4d", (cell=='d'? 999 : 3));
        putchar('\n');
    }
}

Full Demo Live

• Naive indexing Helper version: Live On Coliru

  Compilation: (on coliru!)

   real    0m0.562s
   user    0m0.432s
   sys 0m0.124s
  

  Runtime (on coliru!):

   real    0m0.005s
   user    0m0.000s
   sys 0m0.004s
  

• Boost Multi-Array version: Compiler Explorer/Coliru

Executable size is 118k (GCC) or 119k (clang) on my system (both approaches).