Island Perimeter LeetCode solution in Java

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class Solution {
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  public int islandPerimeter(int[][] grid) {
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    if (grid == null || grid.length == 0) return 0;
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    int row = grid.length, col = grid[0].length;
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    int perimeter = 0;
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    for (int i = 0; i < row; i++) {
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      for (int j = 0; j < col; j++) {
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        if (grid[i][j] == 1) {
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          perimeter += 4;
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          if (i > 0 && grid[i - 1][j] == 1) {
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            perimeter -= 2;
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          }
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          if (j > 0 && grid[i][j - 1] == 1) {
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            perimeter -= 2;
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          }
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        }
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      }
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    }
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    return perimeter;
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  }
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}