八皇后算法

来源：互联网发布：证件制作软件手机版编辑：程序博客网时间：2024/06/16 14:40

1.下一个棋子后检查算法：

package resultQueue;public class Test {    private int[] plate;    private int n;    private int count;    public Gaoziheng(int n) {        this.n = n;        plate = new int[n];    }    public static void main(String args[]) {        for (int i = 1; i <= 8; i++) {            long start = System.currentTimeMillis();            Gaoziheng gaoziheng = new Gaoziheng(i);             gaoziheng.tryPutQueen();            long cost = System.currentTimeMillis() - start;            System.out.println(i + "宫格一共耗时" + cost + "ms, 一共" + gaoziheng.count + "种排法");        }    }    public void tryPutQueen() {        tryPutQueen(0);    }    public void tryPutQueen(int row) {        for (int i = 0; i < n; i++) {            if (checkPoint(row, i)) {                putQueen(row, i);                if (row == n - 1) {                    count++;                    continue;                }                tryPutQueen(row + 1);//              removeQueen(row);            }        }    }    private boolean checkPoint(int row, int col) {        for (int i = 0; i < row; i++) {            if (plate[i] == col) {                return false;            }            if (Math.abs(plate[i] - col) == Math.abs(row - i)) {                return false;            }        }        return true;    }    public void putQueen(int row, int col) {        plate[row] = col;    }}

2.通过第一颗和第二课的斜率排除

package resultQueue;public class Test2 {    private int[][] plate;    private int[] queens;    private int n;    private int count;    public Test2(int n) {        this.n = n;        plate = new int[n][n];        queens = new int[n];    }    public static void main(String args[]) {        for (int i = 1; i <= 8; i++) {            long start = System.currentTimeMillis();            Liuhanhui liuhanhui = new Liuhanhui(i);             liuhanhui.tryPutQueen();            long cost = System.currentTimeMillis() - start;            System.out.println(i + "宫格一共耗时" + cost + "ms, 一共" + test2.count + "种排法");        }    }    public void tryPutQueen() {        tryPutQueen(0);    }    public void tryPutQueen(int row) {        for (int i = 0; i < n; i++) {            if (plate[row][i] == 0) {                putQueen(row, i);                if (row == n - 1) {                    count++;                    print();                    continue;                }                tryPutQueen(row + 1);                removeQueen(row, i);            }        }    }    private void print() {        StringBuilder sb = new StringBuilder();             for (int i : queens) {                  sb.append(i).append("\t");             }             sb.append("\n");        System.out.println(sb.toString());    }    private void removeQueen(int row, int col) {        for (int i = row + 1; i < n; i++) {            recoverSpace(i, col);            recoverSpace(i, col - (i - row));            recoverSpace(i, col + (i - row));        }    }    public void putQueen(int row, int col) {        queens[row] = col;        for (int i = row + 1; i < n; i++) {            killSpace(i, col);            killSpace(i, col - (i - row));            killSpace(i, col + (i - row));        }    }    public void killSpace(int x, int y) {        if (x >= n || y >= n || x < 0 || y < 0) return;        plate[x][y] += 1;    }    public void recoverSpace(int x, int y) {        if (x >= n || y >= n || x < 0 || y < 0) return;        plate[x][y] -= 1;    }}

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