<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 {
    int rows;
    int cols;
    int perimeter = 0;
public:
    int islandPerimeter(vector<vector<int>>& grid) {
        rows = grid.size();
        cols = grid[0].size();

        // We only need to find the first land cell and explore the entire island
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                if (grid[i][j] == 1) {
                    // Use DFS to explore the island and calculate the perimeter
                    vector<vector<bool>> visited(rows, vector<bool>(cols, false));
                    exploreIsland(grid, visited, i, j);
                    return perimeter;  // Return perimeter after exploring the island
                }
            }
        }
        return perimeter;
    }

    void exploreIsland(vector<vector<int>>& grid, vector<vector<bool>>& visited, int row, int col) {
        // If out of bounds or water, contribute to perimeter
        if (row < 0 || row >= rows || col < 0 || col >= cols || grid[row][col] == 0) {
            perimeter++;
            return;
        }

        // If the cell is already visited, return
        if (visited[row][col]) return;
        
        // Mark the cell as visited
        visited[row][col] = true;

        // Explore in all 4 directions
        exploreIsland(grid, visited, row + 1, col);  // Down
        exploreIsland(grid, visited, row - 1, col);  // Up
        exploreIsland(grid, visited, row, col + 1);  // Right
        exploreIsland(grid, visited, row, col - 1);  // Left
    }
};
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