Java解“数独”之二

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用到Shudu和Grid两个类,

运行 Shudu里的main方法，

读取的是本地文件

/**  
 * 创建时间：2017-1-11 
 * @author Dsz    
 */
import java.io.FileReader;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

public class ShuDu2 {
	public static void main(String[] args) throws Exception {
		SimpleDateFormat dfs = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
		Date begin = dfs.parse(dfs.format(new Date()));

		String arg = "D:\\ENV\\workspace\\zisNumber\\shudu.txt";
		FileReader rd = new FileReader(arg);
		while (true) {
			Grid grid = Grid.create(rd);
			if (grid == null) {
				break;
			}
			List solutions = new ArrayList();

			solve(grid, solutions);

			printSolutions(grid, solutions);
		}

		Date end = dfs.parse(dfs.format(new Date()));
		long between = end.getTime() - begin.getTime();
		System.out.println("use Time:" + between + "ms");
	}

	private static void solve(Grid grid, List solutions) {

		if (solutions.size() >= 2) {
			return;
		}

		int loc = grid.findEmptyCell();

		if (loc < 0) {
			solutions.add(grid.clone());
			return;
		}

		for (int n = 1; n < 10; n++) {
			if (grid.set(loc, n)) {
				solve(grid, solutions);

				grid.clear(loc);
			}
		}
	}

	private static void printSolutions(Grid grid, List solutions) {
		System.out.println("Original");
		System.out.println(grid);

		if (solutions.size() == 0) {
			System.out.println("Unsolveable");
		} else if (solutions.size() == 1) {
			System.out.println("Solved");
		} else {
			System.out.println("At least two solutions");
		}

		for (int i = 0; i < solutions.size(); i++) {
			System.out.println(solutions.get(i));
		}
		System.out.println();
		System.out.println();
	}
}

/**  
 * 创建时间：2017-1-11 
 * @author Dsz    
 */
import java.io.Reader;

public class Grid implements Cloneable {
	int[] cells = new int[81];

	int[] colsSet = new int[9];

	int[] rowsSet = new int[9];

	int[] subgridSet = new int[9];

	public static Grid create(Reader rd) throws Exception {
		Grid grid = new Grid();

		for (int loc = 0; loc < grid.cells.length;) {

			int ch = rd.read();

			if (ch < 0) {

				return null;
			}
			if (ch == '#') {

				while (ch >= 0 && ch != '\n' && ch != '\r') {
					ch = rd.read();
				}
			} else if (ch >= '1' && ch <= '9') {

				grid.set(loc, ch - '0');
				loc++;
			} else if (ch == '.' || ch == '0') {

				loc++;
			}
		}
		return grid;
	}

	public int findEmptyCell() {
		for (int i = 0; i < cells.length; i++) {
			if (cells[i] == 0) {
				return i;
			}
		}
		return -1;
	}

	public boolean set(int loc, int num) {
		// Compute row and column
		int r = loc / 9;
		int c = loc % 9;
		int blockLoc = (r / 3) * 3 + c / 3;

		boolean canSet = cells[loc] == 0 && (colsSet[c] & (1 << num)) == 0
				&& (rowsSet[r] & (1 << num)) == 0
				&& (subgridSet[blockLoc] & (1 << num)) == 0;
		if (!canSet) {
			return false;
		}

		cells[loc] = num;
		colsSet[c] |= (1 << num);
		rowsSet[r] |= (1 << num);
		subgridSet[blockLoc] |= (1 << num);
		return true;
	}

	public void clear(int loc) {
		// Compute row and column
		int r = loc / 9;
		int c = loc % 9;
		int blockLoc = (r / 3) * 3 + c / 3;

		int num = cells[loc];
		cells[loc] = 0;
		colsSet[c] ^= (1 << num);
		rowsSet[r] ^= (1 << num);
		subgridSet[blockLoc] ^= (1 << num);
	}

	public Grid clone() {
		Grid grid = new Grid();
		grid.cells = cells.clone();
		grid.colsSet = colsSet.clone();
		grid.rowsSet = rowsSet.clone();
		grid.subgridSet = subgridSet.clone();
		return grid;
	}

	public String toString() {
		StringBuffer buf = new StringBuffer();
		for (int r = 0; r < 9; r++) {
			if (r % 3 == 0) {
				buf.append("-------------------------\n");
			}
			for (int c = 0; c < 9; c++) {
				if (c % 3 == 0) {
					buf.append("| ");
				}
				int num = cells[r * 9 + c];
				if (num == 0) {
					buf.append("0 ");
				} else {
					buf.append(num + " ");
				}
			}
			buf.append("|\n");
		}
		buf.append("-------------------------");
		return buf.toString();
	}
}

输出结果：

Original
-------------------------
| 8 0 0 | 0 0 0 | 0 0 0 |
| 0 0 3 | 6 0 0 | 0 0 0 |
| 0 7 0 | 0 9 0 | 2 0 0 |
-------------------------
| 0 5 0 | 0 0 7 | 0 0 0 |
| 0 0 0 | 0 4 5 | 7 0 0 |
| 0 0 0 | 1 0 0 | 0 3 0 |
-------------------------
| 0 0 1 | 0 0 0 | 0 6 8 |
| 0 0 8 | 5 0 0 | 0 1 0 |
| 0 9 0 | 0 0 0 | 4 0 0 |
-------------------------
Solved
-------------------------
| 8 1 2 | 7 5 3 | 6 4 9 |
| 9 4 3 | 6 8 2 | 1 7 5 |
| 6 7 5 | 4 9 1 | 2 8 3 |
-------------------------
| 1 5 4 | 2 3 7 | 8 9 6 |
| 3 6 9 | 8 4 5 | 7 2 1 |
| 2 8 7 | 1 6 9 | 5 3 4 |
-------------------------
| 5 2 1 | 9 7 4 | 3 6 8 |
| 4 3 8 | 5 2 6 | 9 1 7 |
| 7 9 6 | 3 1 8 | 4 5 2 |
-------------------------


use Time:561ms

 

转载于:https://my.oschina.net/u/2968607/blog/822970