<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:
    void visitisland(vector<vector<int>>& grid,int r,int c,int row,int col,int *peri)
    {

        if(r >= row || c >= col || r<0 || c < 0 ||grid[r][c]!=1)
        return;

        grid[r][c] = 2;

            *peri += (r-1 < 0 || grid[r-1][c] == 0) +
                    (r+1 >= row || grid[r+1][c]==0) +
                    (c-1 < 0 || grid[r][c-1]==0)+
                    (c+1 >= col || grid[r][c+1]==0);

            visitisland(grid,r-1,c,row,col,peri); //left
            visitisland(grid,r+1,c,row,col,peri); //right
            visitisland(grid,r,c-1,row,col,peri); //up
            visitisland(grid,r,c+1,row,col,peri); //down
            return;

        
    }
    int islandPerimeter(vector<vector<int>>& grid) {
        int col = grid[0].size();
        int row = grid.size();
        int peri =0;
        for(int r=0;r<row;r++)
        {
            for(int c=0;c<col;c++)
            {
                if(grid[r][c]==1)
                {
                visitisland(grid,r,c,row,col,&peri);
                return peri;
                }
                
            }
        }
        return 0;
    }
};
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