Queen's puzzle

[Erhard Henkes]

s. https://www.c-plusplus.net/forum/p2539980

Hier der entsprechende Code in C++:

#include <chrono>
#include <ctime>
#include <ratio>
#include <iostream>

float tps = 0.0f;  // time per solution
int N = 1;         // number of fields (normal chess board: 8)
int x[27];         // column of chess queen, row i.
int solutions = 0; // number of solutions

void printHorizontalBorder()
{
  std::cout << "+";
  for (int i=0; i<N; ++i)
  {
    std::cout << "--";
  }
  std::cout << "+" << std::endl;
}

void showBoard()
{
  printHorizontalBorder();
  for (int i=0; i<N; ++i)
  {
    std::cout << "|";
    for (int j=0; j<N; j++)
    {
      if (j==x[i])
        std::cout << "x ";
      else
        std::cout << "  ";
    }
    std::cout << "|\n";
  }
  printHorizontalBorder();
  std::cout << std::endl;
}

bool check(int a, int b)
{
  for (int i=0; i<b; ++i)
    if ((x[i]==a) || (abs(x[i]-a)==abs(i-b)))
        return false;
  return true;
}

void test(int n)
{
  if (n==N)
  {
     ++solutions;
     if (N<7)
       showBoard();
  }
  else
  {
    for (int i=0; i<N; ++i)
    {
      if (check(i,n))
      {
        x[n]=i;
        test(n+1);
      }
    }
  }
}

int main()
{
  int M = 27;
  while (N<=M)
  {
    solutions = 0;
    auto t1 = std::chrono::system_clock::now();
    test(0);
    auto t2 = std::chrono::system_clock::now();
    float timespan = std::chrono::duration<float>(t2-t1).count();
    float tps = 0.0f;
    if (solutions)
    {
        tps = 1000 * timespan/(float)solutions;
    }
    std::cout << "N = " << N << "\ttime = " << timespan << " s \tsolutions = " << solutions;
    if (N>10)
        std::cout << "\ttps = " << tps << " ms\n";
    std::cout << std::endl;
    N += 1;
  }
  return 0;
}