<p>Given an <code>m x n</code> 2D binary grid <code>grid</code> which represents a map of <code>&#39;1&#39;</code>s (land) and <code>&#39;0&#39;</code>s (water), return <em>the number of islands</em>.</p>

<p>An <strong>island</strong> is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> grid = [
  [&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;1&quot;,&quot;0&quot;],
  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;],
  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
  [&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;]
]
<strong>Output:</strong> 1
</pre>

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

<pre>
<strong>Input:</strong> grid = [
  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
  [&quot;1&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;,&quot;0&quot;],
  [&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;0&quot;,&quot;0&quot;],
  [&quot;0&quot;,&quot;0&quot;,&quot;0&quot;,&quot;1&quot;,&quot;1&quot;]
]
<strong>Output:</strong> 3
</pre>

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

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 300</code></li>
	<li><code>grid[i][j]</code> is <code>&#39;0&#39;</code> or <code>&#39;1&#39;</code>.</li>
</ul>

class Solution {
public:
   
    int numIslands(vector<vector<char>>& grid) {
        int rows = grid.size();
        int cols = grid[0].size();
        int cc = 0;
        for(int r = 0;r<rows;r++){
            for(int c = 0;c<cols;c++){
                if(grid[r][c]=='0'){
                    continue;
                } 
                cc++;
                grid[r][c] = '0';
                queue<pair<int,int>> qu;
                qu.push({r,c});
                while(not qu.empty()){
                    auto curr = qu.front();
                    qu.pop();
                    int currRow = curr.first;
                    int currCol = curr.second;
                    if(currRow-1>=0 and grid[currRow - 1][currCol]=='1'){
                        qu.push({currRow - 1,currCol});
                        grid[currRow - 1][currCol] = '0';
                    }
     if(currRow+1<rows and grid[currRow + 1][currCol] =='1'){
                        qu.push({currRow + 1,currCol});
                        grid[currRow + 1][currCol] = '0';
                    }
                     if(currCol-1>=0 and grid[currRow][currCol-1]=='1'){
                        qu.push({currRow,currCol-1});
                        grid[currRow][currCol-1] = '0';
                    }
                     if(currCol+1<cols and grid[currRow][currCol+1]=='1'){
                        qu.push({currRow,currCol+1});
                        grid[currRow][currCol+1] = '0';
                    }
                }
            }
        }
        return cc;
    }
};
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