<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>

from collections import deque

class Solution:


    def numIslands(self, grid: List[List[str]]) -> int:
        m = len(grid)
        n = len(grid[0])

        def get_nbrs(i,j):
            nbrs = []
            if i - 1 >= 0:
                nbrs.append((i-1,j))
            if i + 1 <= m-1:
                nbrs.append((i+1,j))
            if j - 1 >= 0:
                nbrs.append((i,j-1))
            if j + 1 <= n-1:
                nbrs.append((i,j+1))
            return nbrs


        all_1s = deque()
        for i in range(m):
            for j in range(n):
                if grid[i][j] == "1":
                    all_1s.append((i,j))
        
        cnt = 0
        while len(all_1s) > 0:
            i,j = all_1s.popleft()
            que = deque(get_nbrs(i,j))
            while len(que) > 0:
                i_,j_ = que.popleft()
                if grid[i_][j_] == "1":
                    grid[i_][j_] = "c"
                    if (i_,j_) in all_1s:
                        all_1s.remove((i_,j_))
                    for i__,j__ in get_nbrs(i_,j_):
                        que.append((i__,j__))
            cnt += 1
        
        return cnt





        
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