Method dfs

java/0417-pacific-atlantic-water-flow.java:32–46

(
        int[][] heights,
        int i,
        int j,
        int prev,
        boolean[][] ocean
    )

    }

    private void dfs(
        int[][] heights,
        int i,
        int j,
        int prev,
        boolean[][] ocean
    ) {
        if (i < 0 || i >= ocean.length || j < 0 || j >= ocean[0].length) return;
        if (heights[i][j] < prev || ocean[i][j]) return;

        ocean[i][j] = true;
        for (int[] d : dir) {
            dfs(heights, i + d[0], j + d[1], heights[i][j], ocean);
        }
    }
}