Using java language eight queens problem

Eight queens problem, in a 8X8 board, place the eight pieces, each piece up and down, the upper left lower left upper right lower right direction no other piece. The correct answer is 92, then implemented in java language.

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solution:

package eightQuen;

/**
 * 八皇后问题
 * 
 * @author 83771
 *
 */
public class eight {
    // 定义一个数组 表示棋盘
    public static Integer[][] checkerBoard = new Integer[8][8];
    // 棋盘副本
    public static Integer[][] checkerBoardCopy = new Integer[8][8];

    // 计数器 用于计数有多少种方法
    public static Integer jishu = 1;

    // 定义横竖斜方向上是否有棋子
    public static boolean flag1 = true;
    public static boolean flag2 = true;
    public static boolean flag3 = true;
    public static boolean flag4 = true;

    // 初始化一个棋盘 8x8
    public static void init() {
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                System.out.print(0 + "    ");
                checkerBoard[i][j] = 0;
            }
            System.out.println();
        }
        checkerBoardCopy = checkerBoard;
    }

    // 递归测试方法
    public static void startTest(int row) {
        for (int col = 0; col < 8; col++) {
            if (checkCheet(row, col, checkerBoardCopy) == 1) {
                if (row < 7) {
                    startTest(++row);
                    --row;
                }
            }
            // 该行重新赋值为0    进行下一次判断
            checkerBoardCopy[row][col] = 0;
        }
    }

    // 检查是否危险
    // row行
    // col列
    public static int checkCheet(int row, int col, Integer[][] checkerBoardCopy) {
        flag1 = true;
        flag2 = true;
        flag3 = true;
        flag4 = true;
        // 行方向上是否满足条件
        for (int i = 0; i < 8; i++) {
            if (checkerBoardCopy[row][i] == 1) {
                flag1 = false;
                break;
            }
        }
        // 列方向上是否满足条件
        for (int j = 0; j < 8; j++) {
            if (checkerBoardCopy[j][col] == 1) {
                flag2 = false;
                break;
            }
        }
        // 右下方向
        for (int i = row, j = col; i < 8 & j < 8; i++, j++) {
            if (checkerBoardCopy[i][j] == 1) {
                flag3 = false;
                break;
            }
        }
        // 左上方向
        for (int i = row, j = col; i >= 0 & j >= 0; i--, j--) {
            if (checkerBoardCopy[i][j] == 1) {
                flag3 = false;
                break;
            }
        }
        // 左下方向
        for (int i = row, j = col; i < 8 & j >= 0; i++, j--) {
            if (checkerBoardCopy[i][j] == 1) {
                flag4 = false;
                break;
            }
        }
        // 右上方向
        for (int i = row, j = col; i >= 0 & j < 8; i--, j++) {
            if (checkerBoardCopy[i][j] == 1) {
                flag4 = false;
                break;
            }
        }
        if (flag1 & flag2 & flag3 & flag4) {
            // 若为真 增此点的值赋为1
            checkerBoardCopy[row][col] = 1;
            // 如果已经判断到最后一行 并且最后一行也符合情况 打印整个棋盘
            if (row == 7) {
                printCheets(checkerBoardCopy);
            }
            return 1;
        }
        return 0;
    }

    // 打印棋盘方法
    public static void printCheets(Integer[][] checkerBoardCopy) {
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                System.out.print(checkerBoardCopy[i][j] + "   ");
            }
            System.out.println();
        }
        System.out.println("=================" + jishu++);
    }

    public static void main(String[] args) {
        init();
        startTest(0);
    }

}

It can be run directly after copy. Remember what this code.