回溯法

vector
     
      
        > solveNQueens(int n) {        // Note: The Solution object is instantiated only once and is reused by each test case.        vector
       
        
         > res;        vector
         
           queens;        vector
          
            cols(n,false); vector
           
             diag(2*n,false); vector
            
              ardiag(2*n,false); dfs(0,n,queens,cols,diag,ardiag,res); return res; } void dfs(int row,int n,vector
             
              & queens,vector
              
               & cols,vector
               
                & diag,vector
                
                 & ardiag,vector
                 
                  
                   >& res) { if(row==n) { generate(queens,res); return; } for(int i=0;i
                   

& queens,vector

>& res) { int n = queens.size(); vector

tmp(n,string(n,'.')); for(int i=0;i