2020 优必选笔试题——N皇后

90%

#include

using namespace std;

int n;
vector flag(n, 0);

struct queen {
   int x;
   int y;
};

stack s, temp;
int result = 0;

bool judge(int x, int y) {
   stack tmp = s;
   while (!tmp.empty()) {
      queen q = tmp.top();
      if (flag[y] || (abs(q.x - x) == abs(q.y - y))) {
         return false;
      }
      tmp.pop();
   }
   return true;
}

void sovled() {
   if (s.empty()) {
      queen q;
      q.x = 0;
      for (q.y = 0; q.y < n; q.y++) {
         s.push(q);
         flag[q.y] = true;
         sovled();
         s.pop();
         flag[q.y] = false;
      }
   }
   else {
      if (s.size() == n) {
         temp = s;
         result++;
         return;
      }
      else {
         queen q;
         q.x = s.top().x + 1;
         for (q.y = 0; q.y < n; q.y++) {
            if (judge(q.x, q.y)) {
               s.push(q);
               flag[q.y] = true;
               sovled();
               s.pop();
               flag[q.y] = false;
            }
         }
      }
   }
}

int main()
{
   cin >> n;
   sovled();
   cout << "Total count: " << result;
   return 0;
}