8Queens in 10 Lines of C++

8Queens.cpp

#include <iostream>
const int N = 8;

int queen[N];

bool check(int n) {
  for (int i = 0; i < n; i++) {
    int x = n - i;
    int y = queen[n] - queen[i];

    if (y == 0 || abs(x) == abs(y)) return false;
  }
  return true;
}

void dfs(int n) {
  if (n == N) {
    for (int i : queen)
      std::cout << i << " ";
    std::cout << std::endl;
    
  }
  for (int i = 0; i < N; i++) {
    queen[n] = i;
    if (check(n))
      dfs(n + 1);
  }
}

int main() {
  dfs(0);
  return 0;
}

8Queens10Line.cpp

#include <iostream>
int N = 8, queen[8];
int dfs(int n, int result = 0) {
  if (n == N) return 1; else for (int i = 0, flag = 0; i < N; queen[n] = i, i++, result += (flag == 0 ? dfs(n + 1) : 0), flag = 0) for (int j = 0; j < n; j++) if (i - queen[j] == 0 || abs(n - j) == abs(i - queen[j])) flag = 1;
  return result;
}
int main() {
  std::cout << dfs(0) << std::endl;
  return 0;
}