Using Java to implement some common problems

Eight Queens

1  Public classEightqueen {2 3     Private Static Final intROW = 4;4     Private Static Final intCOL = 4;5 6     Private Static intCount = 0;//Eight the number of the Queen's Solutions7 8     Private Static Boolean[] maps =New Boolean[ROW] [COL];//Initializes a two-dimensional array, simulates the 8*8 checkerboard, and the default value is false to indicate no queen9 Ten     //How to put the Queen?  One     /** A * Place the Queen of the first row -      * @paramrow starts with the Queen on line No. 0. -      */ the      Public Static voidPutqueen (introw) { -  -         //Export of recursion -         if(row = = row) {//row=8, the 9th row, then the front 8 rows is ok + Printqueen (); -             return; +         } A  at         //Put the Queen in column J of row No. -          for(intj = 0; J < COL; J + +) { -             //If you can put it, put the Queen at that point. -             if(IsOK (Row, J)) { -MAPS[ROW][J] =true; -Putqueen (row + 1);//after the line is put down and put down a line "recursion to put the Queen", the algorithm has jumped inMAPS[ROW][J] =false;//backtracking, when the row+1 line piece is not satisfied, will go back to the first row -             } to         } +     } -  the     //if you want to place the Queen at the (x, y) point, you need to first determine whether the point can be placed *      Public Static BooleanIsOK (intXinty) { $ Panax Notoginseng         //Traverse a two-dimensional array to determine whether there are queens in 4 directions -          for(inti = 0; i < ROW; i++) { the              for(intj = 0; J < COL; J + +) { +                 //positive hypotenuse x-y fixed value, inverse bevel x+y as fixed value A                 if(i = = x | | j = = Y | | i-j = = XY | | i + j = = x +y) { the                     //judge whether there is a queen in 4 directions +                     if(Maps[i][j]) {//returns False if a queen is placed at that point -                         return false; $                     } $                 } -             } -         } the  -         return true;Wuyi     } the  -      Public Static voidPrintqueen () { Wu  -System.out.println ("++count" + "One Solution")); AboutSystem.out.println ("*******************"); $          for(inti = 0; i < ROW; i++) { -              for(intj = 0; J < COL; J + +) { -                 if(Maps[i][j]) { -System.out.print ("Q"); A}Else { +System.out.print ("*"); the                 } -             } $ System.out.println (); the         } the     } the  the     /** - * 4 Queen for the poor lifting method in      */ the     Private Static voidQueen () { the          About          for(inti = 0;i < 4;++i) the              for(intj = 0;j < 4;++j) the                  for(intK = 0;k < 4;++k) the                      for(intm = 0; M < 4;++m) +                         if(!conflusion (i,j,k,m)) { -System.out.println ("[" +i+ "," +j+ "," + K + "," + M + "]"); the                         }Bayi          the     }     the  -     Private Static BooleanConflusion (intIintJintKintm) { -          the         returnj = = I | | K = = I | | m = = I | | K = = J | | m = = J | | K = =m the|| Math.Abs (i-j) = = 1 | | Math.Abs (i-k) = = 2 the|| Math.Abs (i-m) = = 3 | | Math.Abs (j-k) = = 1 the|| Math.Abs (j-m) = = 2 | | Math.Abs (k-m) = = 1; -     } the  the      Public Static voidMain (string[] args) { the 94System.out.println ("Backtracking method for 4 Queens"); thePutqueen (0);//let the Queen begin on line No. 0. theSystem.out.println ("Exhaustive method for solving 4 Queens"); the Queen ();98     } About}

Using Java to implement some common problems