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++;

        }

    }

};

或许可以用状态压缩？