<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) {
        queue<pair<int, int>> q;
        int rows = grid.size();
        int cols = grid[0].size();
        
        // Find the first land cell and push it to the queue
        bool found = false;
        for(int i = 0; i < rows; i++) {
            for(int j = 0; j < cols; j++) {
                if(grid[i][j] == 1) {
                    q.push({i, j});
                    found = true;
                    break;
                }
            }
            if (found) break;
        } 
        
        int perimeter = 0;
        vector<vector<int>> visited(rows, vector<int>(cols, 0));

        while(!q.empty()) {
            pair<int, int> front = q.front();
            int r = front.first;
            int c = front.second;
            q.pop();
            
            if (visited[r][c]) continue;
            visited[r][c] = 1;

            int adj = 0;
            
            // Check adjacent cells and calculate perimeter
            if(r + 1 < rows && grid[r + 1][c] == 1) {
                adj++;
                if(!visited[r + 1][c]) {
                    q.push({r + 1, c});
                }
            }
            if(r - 1 >= 0 && grid[r - 1][c] == 1) {
                adj++;
                if(!visited[r - 1][c]) {
                    q.push({r - 1, c});
                }
            }
            if(c + 1 < cols && grid[r][c + 1] == 1) {
                adj++;
                if(!visited[r][c + 1]) {
                    q.push({r, c + 1});
                }
            }
            if(c - 1 >= 0 && grid[r][c - 1] == 1) {
                adj++;
                if(!visited[r][c - 1]) {
                    q.push({r, c - 1});
                }
            }
            perimeter += (4 - adj);
        }

        return perimeter;
    }
};

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