递归应用--八皇后java解决

最新推荐文章于 2022-08-25 22:50:29 发布

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最新推荐文章于 2022-08-25 22:50:29 发布

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分类专栏：数据结构&算法文章标签：八皇后递归

本文链接：https://blog.youkuaiyun.com/yongbingchao/article/details/41246421

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本文详细阐述了八皇后问题的解决策略，通过递归函数和回溯算法，实现了对棋盘的初始化、皇后位置的分配及冲突检测，并最终打印出所有有效的解决方案。

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<span style="font-size:18px;">package day5;

public class EightQueen {
	public static int num = 1;

	public void Queen(int queenNum) {
		String queenLocation[][] = new String[queenNum][queenNum];
		int c[] = new int[queenNum];//存放皇后所在的列标
		advance(0, queenNum, c, queenLocation);
	}

	private void advance(int k, int queenNum, int c[], String queenLocation[][]) {
		for (int col = 0; col < queenNum; col++) {
			c[k] = col;//列标
			if (isSafe(c, k)) {
				if (k == queenNum - 1) {
					init(queenLocation);
					for (int i = 0; i < queenNum; i++)// 填充棋盘
					{
						queenLocation[i][c[i]] = "X";
					}
					printQueen(queenLocation, num++);// 打印出当前的可行方案
				} else {
					advance(k + 1, queenNum, c, queenLocation);
				}
			}
		}
	}

	private boolean isSafe(int c[], int currentQueenNum) {
		// 当前是第几个皇后，当前和皇后依次和前面的皇后比较
		// currentQueenNum表示当前是第几个皇后
		if (currentQueenNum == 0)
			return true;
		else {
			for (int i = 0; i < currentQueenNum; i++) {
				if (c[i] == c[currentQueenNum]
						|| (c[i] - c[currentQueenNum]) == (i - currentQueenNum)
						|| (c[i] - c[currentQueenNum]) == (currentQueenNum - i))
					return false;
			}
			return true;
		}
	}

	/**
	 * 对棋盘的初始化
	 * 
	 * @param queenLocation
	 */
	private void init(String[][] queenLocation) {
		int n = queenLocation.length;
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				queenLocation[i][j] = "0";
			}
		}
	}

	/**
	 * 打印棋盘
	 * 
	 * @param queenLocation
	 * @param num
	 */
	private void printQueen(String[][] queenLocation, int num) {
		int n = queenLocation.length;
		String queenString = "";
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < n; j++) {
				if (j == (n - 1)) {
					queenString += queenLocation[i][j] + "\n";
				} else {
					queenString += queenLocation[i][j] + "   ";
				}
			}
		}
		System.out.println("第" + num + "种解决方案：");
		System.out.println(queenString);
	}

	public static void main(String[] args) {
		EightQueen queen = new EightQueen();
		int queenNumber = 8;// 皇后数量
		queen.Queen(queenNumber);
	}
}
</span>