解题思路：

dfs

public class Main {static final int N = 4;static int[][] visited = new int[N][N];static int count;public static void main(String[] args) {for (int i = 0; i < N; i++) { //16种位置开始的可能for (int j = 0; j < N; j++) {dfs(i, j, 1);}}System.out.println(count);}public static void dfs(int x, int y, int step) {if (visited[x][y] == 0) {visited[x][y] = 1;dfs_two(x, y, step + 1);visited[x][y] = 0;}}public static void dfs_two(int x, int y, int step) {if (step == 17) {count++;return;}if (x > 0) dfs(x - 1, y, step); //上if (x + 1 < N) dfs(x + 1, y, step); //下if (y > 0) dfs(x, y - 1, step); //左if (y + 1 < N) dfs(x, y + 1, step); //右}}