1 public class Solution  2 {  3     public static void main(String[] args)  4     {  5         int[][] chessboard = new int[8][8];  6   7         while(true)  8         {  9             putQueens(chessboard); 10  11             if(judgeCorrect(chessboard) == true) 12             { 13                 drawChessboard(chessboard); 14                 break; 15             } 16             else 17                 clearChessboard(chessboard); 18         }     19     } 20  21  22     //put 8 queens on the chessboard randomly 23     public static void putQueens(int[][] array) 24     { 25         int position; 26      27         for(int i = 0; i < 8; i++) 28         { 29             position = (int)(Math.random() * 8); 30             array[i][position] = 1; 31         } 32     } 33  34     //clear the chessboard 35     public static void clearChessboard(int[][] array) 36     { 37         for(int i = 0; i < 8; i++) 38             for(int j = 0; j < 8; j++) 39                 array[i][j] = 0; 40     } 41  42     //judge if there is only one chess in a row 43     public static boolean judgeRow(int[][] array, int x, int y) 44     { 45         for(int i = y - 1; i >= 0; i--) 46             if(array[x][i] == 1) 47                 return false; 48         for(int i = y + 1; i < 8; i++) 49             if(array[x][i] == 1) 50                 return false; 51         return true; 52     } 53  54     //judge if there is only one chess in a column 55     public static boolean judgeColumn(int[][] array, int x, int y) 56     { 57         for(int i = x - 1; i >= 0; i--) 58             if(array[i][y] == 1) 59                 return false; 60         for(int i = x + 1; i < 8; i++) 61             if(array[i][y] == 1) 62                 return false; 63         return true; 64     } 65  66     //judge if there is only one chess in the lean from left-top to right-bottom 67     public static boolean judgeLeanTopToBottom(int[][] array, int x, int y) 68     { 69         for(int i = x - 1, j = y - 1; i >= 0 && j >= 0; i--, j--) 70             if(array[i][j] == 1) 71                 return false; 72         for(int i = x + 1, j = y + 1; i < 8 && j < 8; i++, j++) 73             if(array[i][j] == 1) 74                 return false; 75         return true; 76     } 77  78     //judge if there is only one chess in the lean from left-bottom to right-top 79     public static boolean judgeLeanBottomToTop(int[][] array, int x, int y) 80     { 81         for(int i = x + 1, j = y - 1; i < 8 && j >= 0; i++, j--) 82             if(array[i][j] == 1) 83                 return false; 84         for(int i = x - 1, j = y + 1; i >= 0 && j < 8; i--, j++) 85             if(array[i][j] == 1) 86                 return false; 87         return true; 88     } 89  90     //judge if all the queens are put correctly 91     public static boolean judgeCorrect(int[][] array) 92     { 93         int[] putX = new int[8]; 94         int[] putY = new int[8]; 95  96         for(int i = 0; i < 8; i++) 97             for(int j = 0; j < 8; j++) 98                 if(array[i][j] == 1) 99                 {100                     putX[i] = i;101                     putY[i] = j;102                     break;103                 }104 105         for(int i = 0; i < 8; i++)106         {107             if(!(judgeRow(array, putX[i], putY[i]) && judgeColumn(array, putX[i], putY[i]) 108                 && judgeLeanTopToBottom(array, putX[i], putY[i]) && judgeLeanBottomToTop(array, putX[i], putY[i])))109                 return false;110         }111         return true;112     }113 114     public static void drawChessboard(int[][] array)115     {116         for(int i = 0; i < 8; i++)117         {118             for(int j = 0; j < 8; j++)119             {120                 if(array[i][j] == 1)121                     System.out.print("Q");122                 else123                     System.out.print("-");124             }125             System.out.println();126         }127     }128 }