<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 {
private:
    void bfs(int sRow, int sCol, vector<vector<int>>& visited, vector<vector<char>>& grid){
        visited[sRow][sCol] = 1;
        queue<pair<int, int>> q;
        q.push({sRow, sCol});
        int rows = grid.size();
        int cols = grid[0].size();

        while (!q.empty()) {
            int row = q.front().first;
            int col = q.front().second;
            q.pop();

            // Define valid directions for exploring neighbors (up, down, left, right)
            vector<pair<int, int>> directions = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};

            for (auto dir : directions) {
                int nRow = row + dir.first;
                int nCol = col + dir.second;
                if (nRow >= 0 && nRow < rows && nCol >= 0 && nCol < cols &&
                    grid[nRow][nCol] == '1' && !visited[nRow][nCol]) {
                    visited[nRow][nCol] = 1;
                    q.push({nRow, nCol});
                }
            }
        }
    }
public:
    int numIslands(vector<vector<char>>& grid) {
        int rows = grid.size();
        int cols = grid[0].size();

        vector<vector<int>> visited(rows, vector<int>(cols, 0));
        int islandCount = 0;
        for (int row = 0; row < rows; row++) {
            for (int col = 0; col < cols; col++) {
                if (!visited[row][col] && grid[row][col] == '1') {
                    islandCount++;
                    bfs(row, col, visited, grid);
                }
            }
        }
        return islandCount;
    }
};

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