[CareerCup] 9.9 Eight Queens 八皇后问题-优快云博客

本文介绍了一种解决八皇后问题的算法实现，通过深度优先搜索（DFS）递归地放置皇后，并确保任意两个皇后不在同一行、列或对角线上。文章提供了完整的C++代码示例。

9.9 Write an algorithm to print all ways of arranging eight queens on an 8x8 chess board so that none of them share the same row, column or diagonal. In this case, "diagonal" means all diagonals, not just the two that bisect the board.

LeetCode上的原题，请参见我之前的博客N-Queens N皇后问题和N-Queens II N皇后问题之二。

class Solution {
public:
    vector<vector<int> > placeQueens(int n) {
        vector<vector<int> > res;
        vector<int> pos(n, -1);
        placeQueensDFS(pos, 0, res);
        return res;
    }
    void placeQueensDFS(vector<int> &pos, int row, vector<vector<int> > &res) {
        int n = pos.size();
        if (row == n) res.push_back(pos);
        else {
            for (int col = 0; col < n; ++col) {
                if (isValid(pos, row, col)) {
                    pos[row] = col;
                    placeQueensDFS(pos, row + 1, res);
                    pos[row] = -1;
                }
            }
        }
    }
    bool isValid(vector<int> &pos, int row, int col) {
        for (int i = 0; i < row; ++i) {
            if (col == pos[i] || abs(row - i) == abs(col - pos[i])) {
                return false;
            }
        }
        return true;
    }
};