题目:
The n-queens puzzle is the problem of placing n queens on an n×n chessboard such that no two queens attack each other.
Given an integer n, return all distinct solutions to the n-queens puzzle.
Each solution contains a distinct board configuration of the n-queens' placement, where 'Q'
and '.'
both indicate a queen and an empty space respectively.
Example:
Input: 4 Output: [ [".Q..", // Solution 1 "...Q", "Q...", "..Q."], ["..Q.", // Solution 2 "Q...", "...Q", ".Q.."] ] Explanation: There exist two distinct solutions to the 4-queens puzzle as shown above.
代码:
class Solution { public: vector<vector<string>> solveNQueens(int n) { vector<vector<string>> res; vector<int> site(n); deal(res, n, 0, site); return res; } void deal(vector<vector<string> >& res, int n, int row, vector<int> site){ if(row == n){ vector<string> item; for(int i = 0; i < n; i++){ string temp = ""; for(int j = 0; j < n; j++){ if(site[i] == j) temp += 'Q'; else temp += '.'; } item.push_back(temp); } res.push_back(item); return; } for(int j = 0; j < n; j++){ if(isValid(site, row, j)){ site[row] = j; deal(res, n, row+1, site); } } } bool isValid(vector<int> site, int row, int j){ for(int i = 0; i < row; i++){ if(site[i] == j || abs(j - site[i]) == abs(row - i)) return false; } return true; } };