Island Perimeter LeetCode solution in C++

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class Solution {
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 public:
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  int islandPerimeter(vector<vector<int>> &grid) {
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    int ans = 0, row = grid.size(), col = grid[0].size();
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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]) {
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          ans += 4;
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          if (i < row - 1 && grid[i + 1][j]) ans--;
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          if (j < col - 1 && grid[i][j + 1]) ans--;
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          if (j && grid[i][j - 1]) ans--;
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          if (i && grid[i - 1][j]) ans--;
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        }
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      }
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    }
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    return ans;
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  }
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};