由于最近在学习回溯法，所以跟回溯法相关的问题尽量都看下吧。
骑士游历问题的完整描述见：http://blog.csdn.net/sb___itfk/article/details/50905275
我的思路
我的实现如下，还是最简单最粗暴的解法：
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
/**
* Created by clearbug on 2018/2/26.
*/
public class Solution {
public static void main(String[] args) {
Solution s = new Solution();
long startTime = System.currentTimeMillis();
List<List<String>> res = s.traverse(5, 0, 0);
int i = 1;
for (List<String> item : res) {
System.out.println("第 " + i + " 种走法：");
for (String line : item) {
System.out.println(line);
}
i++;
}
long endTime = System.currentTimeMillis();
System.out.println("运行耗时：" + (endTime - startTime) + " ms");
}
public List<List<String>> traverse(int N, int sr, int sc) {
int[][] board = new int[N][N];
board[sr][sc] = 1;
List<List<String>> res = new ArrayList<>();
dfs(board, sr, sc, res);
return res;
}
private void dfs(int[][] board, int sr, int sc, List<List<String>> res) {
if (check(board)) {
List<String> lines = new ArrayList<>();
for (int i = 0; i < board.length; i++) {
lines.add(Arrays.toString(board[i]));
}
res.add(lines);
}
int[] dr = {2, 2, -2, -2, 1, 1, -1, -1};
int[] dc = {1, -1, 1, -1, 2, -2, 2, -2};
for (int i = 0; i < 8; i++) {
int[][] newBoard = deepthCopy(board);
int cr = sr + dr[i];
int cc = sc + dc[i];
if (cr >= 0 && cr < board.length && cc >= 0 && cc < board.length && board[cr][cc] == 0) {
newBoard[cr][cc] = newBoard[sr][sc] + 1;
dfs(newBoard, cr, cc, res);
}
}
}
private int[][] deepthCopy(int[][] board) {
int[][] res = new int[board.length][board.length];
for (int i = 0; i < board.length; i++) {
for (int j = 0; j < board.length; j++) {
res[i][j] = board[i][j];
}
}
return res;
}
private boolean check(int[][] board) {
for (int i = 0; i < board.length; i++) {
for (int j = 0; j < board.length; j++) {
if (board[i][j] == 0) {
return false;
}
}
}
return true;
}
}运行结果如下：
第 301 种走法：
[1, 16, 21, 6, 3]
[10, 5, 2, 15, 20]
[17, 22, 11, 4, 7]
[12, 9, 24, 19, 14]
[23, 18, 13, 8, 25]
第 302 种走法：
[1, 16, 11, 6, 3]
[10, 5, 2, 21, 12]
[15, 22, 17, 4, 7]
[18, 9, 24, 13, 20]
[23, 14, 19, 8, 25]
第 303 种走法：
[1, 16, 11, 6, 3]
[10, 5, 2, 17, 12]
[15, 22, 19, 4, 7]
[20, 9, 24, 13, 18]
[23, 14, 21, 8, 25]
第 304 种走法：
[1, 18, 11, 6, 3]
[10, 5, 2, 17, 12]
[19, 22, 13, 4, 7]
[14, 9, 24, 21, 16]
[23, 20, 15, 8, 25]
运行耗时：4073 ms当 n = 5 时，运行时间已经上 4 秒了。。。可以虽然可以正确运行，但是效率并不 ok
那么，还是去看看 sb___itfk 这位老铁的解法吧：http://blog.csdn.net/sb___itfk/article/details/50905275
