<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 solve(vector<vector<int>>&grid,vector<vector<bool>>&vis,int sr,int sc)
    {
         int n = grid.size();
         int m = grid[0].size();

           queue<pair<int,int>>q;
           q.push({sr,sc});
           vis[sr][sc] = true;
           int peri = 0;

           int delRow[] = {-1,1,0,0};
           int delCol[] = {0,0,-1,1};

           while( !q.empty()){
               auto it = q.front();
               q.pop();
               
               int r = it.first;
               int c = it.second;

               for(int i=0;i<4;i++){
                  int nr = r + delRow[i];
                  int nc = c + delCol[i];

                  if(nr>=0 && nr<n && nc>=0 && nc<m && grid[nr][nc] == 0)peri++;
                  else if((nr < 0 || nr >= n || nc < 0 || nc >= m)) peri++;

                  if(nr>=0 && nr<n && nc>=0 && nc<m && grid[nr][nc] == 1 && !vis[nr][nc]){
                      vis[nr][nc] = true;
                      q.push({nr,nc});
                  }
               }
           }
           return peri;
    }
    int islandPerimeter(vector<vector<int>>& grid) {
        int n = grid.size();
        int m = grid[0].size();

        vector<vector<bool>>vis(n,vector<bool>(m));
        int res = 0;
        for(int i=0;i<n;i++)
           for(int j=0;j<m;j++)
             if(vis[i][j] == false && grid[i][j] == 1){
                vis[i][j] = true;
                res += solve(grid,vis,i,j);
             }
        return res;
       
    }
};
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