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.

For example,

There exist two distinct solutions to the 4-queens puzzle:

[ [".Q..",  // Solution 1  "...Q",  "Q...",  "..Q."], ["..Q.",  // Solution 2  "Q...",  "...Q",  ".Q.."]] 解题思路：经典N皇后问题，代码主要参照晴神宝典103页，P[index]=x表示第index行皇后的位置为x，hashTable[x]=True表示第x行已经有皇后放置了，对角线判断用了绝对值 简化了本来的算法

class Solution {public:    vector
     
      
        >ans;    bool hashTable[100]={
   false};    int P[100]={
   0};    void generateP(int index,int n){        if(index==n+1){            string temp="";            vector
       
        tempAns;            for(int i=1;i<=n;i++){                temp="";                for(int j=1;j<=n;j++)                    temp+='.';                temp[P[i]-1]='Q';             //   cout<
        
         <
         
          > solveNQueens(int n) {        generateP(1,n);        return ans;    }};