<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 n =0;
        int r = grid.size();
        int c = grid[0].size();
        
        queue<pair<int,int>> q;
        
        for(int i=0; i < r; i++){
            for(int j=0; j< c; j++){
                
                if(grid[i][j] == '1'){
                    n++;
                    q.push({i,j});
                    while(!q.empty()){
                        auto t = q.front();
                        int f = t.first;
                        int s = t.second;
                        cout << to_string(t.first)<< endl;
                        q.pop();
                        if (f-1>=0 && grid[f-1][s] == '1') { grid[f-1][s] = '0'; q.push({f-1,s});}
                        if (f+1< r && grid[f+1][s] == '1') { grid[f+1][s] = '0'; q.push({f+1,s});}
                        if (s-1>=0 && grid[f][s-1] == '1') { grid[f][s-1] = '0'; q.push({f,s-1});}
                        if (s+1 <c && grid[f][s+1] == '1') { grid[f][s+1] = '0'; q.push({f,s+1});}
                   }
               }
            }
        
         }
        return n;
    }
};
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