Max Area of Island LeetCode solution in Java

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class Solution {
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  public int maxAreaOfIsland(int[][] grid) {
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    final int rows = grid.length;
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    final int cols = grid[0].length;
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    final int[][] dirrections = new int[][] {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
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    Map<String, List<int[]>> adj = new HashMap<>();
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    boolean[][] visited = new boolean[rows][cols];
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    Queue<String> queue = new LinkedList<>();
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    int res = 0;
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    for (int i = 0; i < grid.length; i++) {
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      for (int j = 0; j < grid[i].length; j++) {
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        List<int[]> list = new ArrayList<>();
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        for (int[] dirrection : dirrections) {
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          int newRow = dirrection[0] + i;
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          int newCol = dirrection[1] + j;
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          boolean isInBoard = newRow >= rows || newRow < 0 || newCol >= cols || newCol < 0;
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          if (!isInBoard) {
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            list.add(new int[] {newRow, newCol, grid[newRow][newCol]});
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          }
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        }
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        adj.put(getNodeStringFormat(i, j, grid[i][j]), list);
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      }
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    }
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    for (int i = 0; i < rows; i++) {
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      for (int j = 0; j < cols; j++) {
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        int count = 0;
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        if (visited[i][j]) continue;
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        queue.add(getNodeStringFormat(i, j, grid[i][j]));
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        while (!queue.isEmpty()) {
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          String currentStr = queue.poll();
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          String[] current = currentStr.split(",");
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          int row = Integer.valueOf(current[0]);
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          int col = Integer.valueOf(current[1]);
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          int isLand = Integer.valueOf(current[2]);
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          if (!adj.containsKey(currentStr)) continue;
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          if (visited[row][col]) continue;
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          if (isLand == 1) count++;
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          visited[row][col] = true;
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          for (int[] item : adj.get(currentStr)) {
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            int newRow = item[0];
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            int newCol = item[1];
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            int newIsLand = item[2];
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            if (!visited[newRow][newCol] && newIsLand == 1 && isLand == 1)
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              queue.add(getNodeStringFormat(newRow, newCol, newIsLand));
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          }
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        }
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        res = Math.max(res, count);
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      }
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    }
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    return res;
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  }
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  private String getNodeStringFormat(int row, int col, int isLand) {
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    StringBuilder sb = new StringBuilder();
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    sb.append(row);
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    sb.append(",");
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    sb.append(col);
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    sb.append(",");
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    sb.append(isLand);
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    return sb.toString();
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  }
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}