LeetCode N-Queens II

class Solution {
private:
int queen_num;
int total;
public:
int totalNQueens(int n) {
queen_num = n;
total = 0;

vector<bool> h(n, false);
vector<bool> v(n, false);
vector<bool> lx(n * 2 + 1, false);
vector<bool> rx(n * 2 + 1, false);

dfs(0, h, v, lx, rx);

return total;
}

void dfs(int level, vector<bool> &h, vector<bool> &v, vector<bool> &lx, vector<bool> &rx) {
if (level == queen_num) {
total++;
return;
}
int row = level;
int col = 0;
while (col < queen_num) {
if (!h[row] && !v[col] && !lx[row + col] && !rx[row + queen_num - col - 1]) {
h[row] = v[col] = lx[row + col] = rx[row + queen_num - col - 1] = true;
dfs(level + 1, h, v, lx, rx);
h[row] = v[col] = lx[row + col] = rx[row + queen_num - col - 1] = false;
}
col++;
}
}
};