更新 0103.水流问题 DFS解法Java版本

problems/kamacoder/0103.水流问题.md

@@ -281,6 +281,78 @@ for (int j = 0; j < m; j++) {
 ## 其他语言版本
 
 ### Java 
+```Java
+public class Main {
+
+    // 采用 DFS 进行搜索
+    public static void dfs(int[][] heights, int x, int y, boolean[][] visited, int preH) {
+        // 遇到边界或者访问过的点，直接返回
+        if (x < 0 || x >= heights.length || y < 0 || y >= heights[0].length || visited[x][y]) return;
+        // 不满足水流入条件的直接返回
+        if (heights[x][y] < preH) return;
+        // 满足条件，设置为true，表示可以从边界到达此位置
+        visited[x][y] = true;
+
+        // 向下一层继续搜索
+        dfs(heights, x + 1, y, visited, heights[x][y]);
+        dfs(heights, x - 1, y, visited, heights[x][y]);
+        dfs(heights, x, y + 1, visited, heights[x][y]);
+        dfs(heights, x, y - 1, visited, heights[x][y]);
+    }
+
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+        int m = sc.nextInt();
+        int n = sc.nextInt();
+
+        int[][] heights = new int[m][n];
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                heights[i][j] = sc.nextInt();
+            }
+        }
+
+        // 初始化两个二位boolean数组，代表两个边界
+        boolean[][] pacific = new boolean[m][n];
+        boolean[][] atlantic = new boolean[m][n];
+
+        // 从左右边界出发进行DFS
+        for (int i = 0; i < m; i++) {
+            dfs(heights, i, 0, pacific, Integer.MIN_VALUE);
+            dfs(heights, i, n - 1, atlantic, Integer.MIN_VALUE);
+        }
+
+        // 从上下边界出发进行DFS
+        for (int j = 0; j < n; j++) {
+            dfs(heights, 0, j, pacific, Integer.MIN_VALUE);
+            dfs(heights, m - 1, j, atlantic, Integer.MIN_VALUE);
+        }
+
+        // 当两个边界二维数组在某个位置都为true时，符合题目要求
+        List<List<Integer>> res = new ArrayList<>();
+        for (int i = 0; i < m; i++) {
+            for (int j = 0; j < n; j++) {
+                if (pacific[i][j] && atlantic[i][j]) {
+                    res.add(Arrays.asList(i, j));
+                }
+            }
+        }
+
+        // 打印结果
+        for (List<Integer> list : res) {
+            for (int k = 0; k < list.size(); k++) {
+                if (k == 0) {
+                    System.out.print(list.get(k) + " ");
+                } else {
+                    System.out.print(list.get(k));
+                }
+            }
+            System.out.println();
+        }
+    }
+}
+
+```
 
 ### Python