<p>You are given <code>row x col</code> <code>grid</code> representing a map where <code>grid[i][j] = 1</code> represents&nbsp;land and <code>grid[i][j] = 0</code> represents water.</p>

<p>Grid cells are connected <strong>horizontally/vertically</strong> (not diagonally). The <code>grid</code> is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).</p>

<p>The island doesn&#39;t have &quot;lakes&quot;, meaning the water inside isn&#39;t connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don&#39;t exceed 100. Determine the perimeter of the island.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img src="https://assets.leetcode.com/uploads/2018/10/12/island.png" style="width: 221px; height: 213px;" />
<pre>
<strong>Input:</strong> grid = [[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]
<strong>Output:</strong> 16
<strong>Explanation:</strong> The perimeter is the 16 yellow stripes in the image above.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,0]]
<strong>Output:</strong> 4
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>row == grid.length</code></li>
	<li><code>col == grid[i].length</code></li>
	<li><code>1 &lt;= row, col &lt;= 100</code></li>
	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
	<li>There is exactly one island in <code>grid</code>.</li>
</ul>

class Solution {
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        int rows = grid.size();
        int cols = grid[0].size();
        int ans = 0;
        queue<pair<int, int>> q;

        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                if (grid[i][j] == 1) {
                    q.push({i, j});
                    break;
                }
            }
            if (q.size() > 0) {
                break;
            }
        }
        vector<pair<int, int>> directions = {{-1, 0}, {0, -1}, {1, 0}, {0, 1}};
        while (q.size() > 0) {
            auto [row, col] = q.front();
            q.pop();
            if (grid[row][col] == 1) {
                grid[row][col] = -1;
                for (auto [dr, dc] : directions) {
                    int newRow = row + dr;
                    int newCol = col + dc;
                    if (newRow == -1 || newCol == -1 || newRow >= rows ||
                        newCol >= cols || grid[newRow][newCol] == 0) {
                        ans++;
                    } else if (grid[newRow][newCol] == 1) {
                        q.push({newRow, newCol});
                    }
                }
            }
        }

        return ans;
    }
};
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