JZ12 矩阵中的路径
1 /* DFS */
2 public class JZ12_1
3 {
4 public static boolean[][] vis;
5 public static int[] dx = new int[]{-1, 1, 0, 0};
6 public static int[] dy = new int[]{0, 0, -1, 1};
7
8 public static boolean hasPath(char[][] matrix, String word)
9 {
10 int m = matrix.length, n = matrix[0].length;
11 vis = new boolean[m][n];
12 for (int i = 0; i < m; i++)
13 for (int j = 0; j < n; j++)
14 if (dfs(matrix, word, i, j, 0)) return true;
15 return false;
16 }
17
18 public static boolean dfs(char[][] matrix, String word, int curX, int curY, int idx)
19 {
20 int m = matrix.length, n = matrix[0].length, nextX = -1, nextY = -1;
21 boolean res = false;
22 if (matrix[curX][curY] != word.charAt(idx)) return false;
23 if (idx == word.length() - 1) return true;
24 vis[curX][curY] = true;
25 for (int i = 0; i < 4; i++)
26 {
27 nextX = curX + dx[i];
28 nextY = curY + dy[i];
29 if (nextX < 0 || nextX >= m || nextY < 0 || nextY >= n || vis[nextX][nextY])
30 continue;
31 res = res || dfs(matrix, word, nextX, nextY, idx + 1);
32 }
33 vis[curX][curY] = false;
34 return res;
35 }
36 }
JZ13 机器人的运动范围
1 /* DFS */
2 public class JZ13_1
3 {
4 public static boolean[][] vis;
5 public static int[] dx = new int[]{-1, 1, 0, 0};
6 public static int[] dy = new int[]{0, 0, -1, 1};
7
8 public static int movingCount(int threshold, int rows, int cols)
9 {
10 vis = new boolean[rows][cols];
11 return dfs(threshold, rows, cols, 0, 0);
12 }
13
14 public static int dfs(int threshold, int m, int n, int curX, int curY)
15 {
16 int nextX = -1, nextY = -1, res = 1;
17 vis[curX][curY] = true;
18 for (int i = 0; i < 4; i++)
19 {
20 nextX = curX + dx[i];
21 nextY = curY + dy[i];
22 if (nextX < 0 || nextX >= m || nextY < 0 || nextY >= n || vis[nextX][nextY] || cal(nextX) + cal(nextY) > threshold)
23 continue;
24 res += dfs(threshold, m, n, nextX, nextY);
25 }
26 return res;
27 }
28
29 public static int cal(int nums)
30 {
31 int res = 0;
32 while (nums != 0)
33 {
34 res += nums % 10;
35 nums /= 10;
36 }
37 return res;
38 }
39 }
