distance_2d_lut_gen.cpp

#include <array>
#include <bitset>
#include <cstdint>
#include <iostream>
#include <limits>
#include <utility>
#include <vector>
 
void print(std::array<std::array<bool, 13>, 13> const& adj)
{
    for (unsigned i{}; adj.size() > i; ++i) {
        for (unsigned j{}; adj[i].size() > j; ++j) {
            std::cout << adj[i][j] << ' ';
        }
        std::cout << '\n';
    }
}
 
[[nodiscard]] std::vector<std::pair<unsigned, unsigned>> generate(unsigned idx)
{
    std::array<std::array<bool, 13>, 13> adj{};
 
    // Center is always there
    adj[4][4] = true;
 
    for (unsigned i{}; 8 > i; ++i) {
        if (4 <= i) {
            adj[i + 1][i + 1] = (idx & (1u << i)) ? true : false;
        } else {
            adj[i][i] = (idx & (1u << i)) ? true : false;
        }
    }
 
    for (unsigned i = 9; 13 > i; ++i) {
        adj[i][i] = true;
    }
 
    // if (1 == idx) {
    //  std::cout << '\n';
    //  print(adj);
    //  exit(0);
    // }
 
    // 0 -> 1
    // 0 -> 3
    // 0 -> 9
    adj[0][1] = adj[0][0] && adj[1][1];
    adj[0][3] = adj[0][0] && adj[3][3];
    adj[0][9] = adj[0][0] && !(adj[1][1] && adj[3][3]);
 
    // 1 -> 2
    // 1 -> 4
    // 1 -> 9
    // 1 -> 10
    adj[1][2]  = adj[1][1] && adj[2][2];
    adj[1][4]  = adj[1][1] && ((!adj[0][0] && !adj[3][3]) || (!adj[2][2] && !adj[5][5]));
    adj[1][9]  = adj[1][1] && !adj[0][0] && adj[3][3];
    adj[1][10] = adj[1][1] && !adj[2][2] && adj[5][5];
 
    // 2 -> 5
    // 2 -> 10
    adj[2][5]  = adj[2][2] && adj[5][5];
    adj[2][10] = adj[2][2] && !(adj[1][1] && adj[5][5]);
 
    // 3 -> 4
    // 3 -> 6
    // 3 -> 9
    // 3 -> 11
    adj[3][4]  = adj[3][3] && ((!adj[0][0] && !adj[1][1]) || (!adj[6][6] && !adj[7][7]));
    adj[3][6]  = adj[3][3] && adj[6][6];
    adj[3][9]  = adj[3][3] && !adj[0][0] && adj[1][1];
    adj[3][11] = adj[3][3] && !adj[6][6] && adj[7][7];
 
    // 4 -> 5
    // 4 -> 7
    // 4 -> 9
    // 4 -> 10
    // 4 -> 11
    // 4 -> 12
    // 4, 4 always exists
    adj[4][5]  = ((!adj[1][1] && !adj[2][2]) || (!adj[7][7] && !adj[8][8]));
    adj[4][7]  = ((!adj[3][3] && !adj[6][6]) || (!adj[5][5] && !adj[8][8]));
    adj[4][9]  = adj[0][0] && !(adj[1][1] && adj[3][3]);
    adj[4][10] = adj[2][2] && !(adj[1][1] && adj[5][5]);
    adj[4][11] = adj[6][6] && !(adj[3][3] && adj[7][7]);
    adj[4][12] = adj[8][8] && !(adj[5][5] && adj[7][7]);
 
    // 5 -> 8
    // 5 -> 10
    // 5 -> 12
    adj[5][8]  = adj[5][5] && adj[8][8];
    adj[5][10] = adj[5][5] && adj[1][1] && !adj[2][2];
    adj[5][12] = adj[5][5] && adj[7][7] && !adj[8][8];
 
    // 6 -> 7
    // 6 -> 11
    adj[6][7]  = adj[6][6] && adj[7][7];
    adj[6][11] = adj[6][6] && !(adj[3][3] && adj[7][7]);
 
    // 7 -> 8
    // 7 -> 11
    // 7 -> 12
    adj[7][8]  = adj[7][7] && adj[8][8];
    adj[7][11] = adj[7][7] && adj[3][3] && !adj[6][6];
    adj[7][12] = adj[7][7] && adj[5][5] && !adj[8][8];
 
    // 8 -> 12
    adj[8][12] = adj[8][8] && !(adj[5][5] && adj[7][7]);
 
    std::vector<std::pair<unsigned, unsigned>> edges;
 
    for (unsigned i{}; adj.size() > i; ++i) {
        for (unsigned j = i + 1; adj[i].size() > j; ++j) {
            if (adj[i][i] && adj[j][j] && adj[i][j]) {
                edges.emplace_back(i, j);
            }
        }
    }
 
    return edges;
}
 
int main(int argc, char* argv[])
{
    for (unsigned i{}; std::numeric_limits<std::uint8_t>::max() >= i; ++i) {
        // std::cout << "Index: " << i << " (" << std::bitset<8>(i) << ")\n";
        std::cout << R"(std::array<std::uint8_t, 25>{)";
        auto a = generate(i);
        std::cout << (2 * a.size());
        for (auto [a, b] : a) {
            std::cout << ", " << a << ", " << b;
        }
        std::cout << "},\n";
    }
 
    return 0;
}