八皇后循环递归回溯实现

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棋盘接口

/** * 棋盘接口 * @author Administrator * */public interface Piece {abstract boolean isRow(int line);abstract boolean isCol(int line,int col);}

棋盘类：

/** * 棋盘 * @author Administrator * */public class Chessboard implements Piece {static boolean[][] che = null;public int row;public int col;private int num=0; public Chessboard (int row,int col){this.che=new boolean[row][col];this.row=row;this.col=col;}//当前行是否能放棋子public boolean isRow(int line){for (int i = 0; i < this.row; i++) {if (che[i][line] == true) {return false;}}return true;}//棋子边角public boolean isCol(int line,int col){int i = 0, j = 0;for (i = line, j = col; i < this.row && j < this.row; i++, j++) { //右下角；if (che[i][j] == true) {return false;}}for (i = line, j = col; i >= 0 && j >= 0; i--, j--) { //左上角；if (che[i][j] == true) {return false;}}for (i = line, j = col; i >= 0 && j < this.row; i--, j++) { // 右上角；if (che[i][j] == true) {return false;}}for (i = line, j = col; i < this.row && j >= 0; i++, j--) { //左下角；if (che[i][j] == true) {return false;}}return true;}public void pr() {//打印满足条件的摆放方法num++;System.out.println("第" + num + "种方式");System.out.print("-------------start-------------");for (int i = 0; i < this.row; i++) {System.out.println();for (int j = 0; j < this.row; j++) {if (che[i][j] == true) {System.out.print("Q  ");} else {System.out.print(". ");}}}System.out.println();System.out.println("-------------end-------------");}}

皇后类

/** * 皇后 * @author Administrator * */public class empress {private Chessboard che=null;private int count=0;private int row=0;public empress(int row,int col){this.che=new Chessboard(row,col);this.row=row;}//主要的递归实现方法   public void mk(int line) {if (line > this.row-1)return;//超过行则退出for (int i = 0; i < this.row; i++) {if (che.isRow(i) && che.isCol(line,i)) { //ture 为可以摆皇后；che.che[line][i] = true; // count++; //if (count > this.row-1) {che.pr();//摆放皇后8个则打印结果 }mk(line + 1);//递归      che.che[line][i] = false; //回溯count--; continue;}}return;}}

启动：

import java.io.BufferedReader;import java.io.InputStreamReader;import java.util.Scanner;import javax.swing.JOptionPane;public class start {public static void main(String[] args) {String inputrow = JOptionPane.showInputDialog("输入行:");int row = Integer.parseInt(inputrow);String inputcol = JOptionPane.showInputDialog("输入列:");int col = Integer.parseInt(inputcol);empress emp=new empress(row,col);emp.mk(0);}}