<p>You are given two <code>m x n</code> binary matrices <code>grid1</code> and <code>grid2</code> containing only <code>0</code>&#39;s (representing water) and <code>1</code>&#39;s (representing land). An <strong>island</strong> is a group of <code>1</code>&#39;s connected <strong>4-directionally</strong> (horizontal or vertical). Any cells outside of the grid are considered water cells.</p>

<p>An island in <code>grid2</code> is considered a <strong>sub-island </strong>if there is an island in <code>grid1</code> that contains <strong>all</strong> the cells that make up <strong>this</strong> island in <code>grid2</code>.</p>

<p>Return the <em><strong>number</strong> of islands in </em><code>grid2</code> <em>that are considered <strong>sub-islands</strong></em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/10/test1.png" style="width: 493px; height: 205px;" />
<pre>
<strong>Input:</strong> grid1 = [[1,1,1,0,0],[0,1,1,1,1],[0,0,0,0,0],[1,0,0,0,0],[1,1,0,1,1]], grid2 = [[1,1,1,0,0],[0,0,1,1,1],[0,1,0,0,0],[1,0,1,1,0],[0,1,0,1,0]]
<strong>Output:</strong> 3
<strong>Explanation: </strong>In the picture above, the grid on the left is grid1 and the grid on the right is grid2.
The 1s colored red in grid2 are those considered to be part of a sub-island. There are three sub-islands.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/06/03/testcasex2.png" style="width: 491px; height: 201px;" />
<pre>
<strong>Input:</strong> grid1 = [[1,0,1,0,1],[1,1,1,1,1],[0,0,0,0,0],[1,1,1,1,1],[1,0,1,0,1]], grid2 = [[0,0,0,0,0],[1,1,1,1,1],[0,1,0,1,0],[0,1,0,1,0],[1,0,0,0,1]]
<strong>Output:</strong> 2 
<strong>Explanation: </strong>In the picture above, the grid on the left is grid1 and the grid on the right is grid2.
The 1s colored red in grid2 are those considered to be part of a sub-island. There are two sub-islands.
</pre>

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

<ul>
	<li><code>m == grid1.length == grid2.length</code></li>
	<li><code>n == grid1[i].length == grid2[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 500</code></li>
	<li><code>grid1[i][j]</code> and <code>grid2[i][j]</code> are either <code>0</code> or <code>1</code>.</li>
</ul>

class Solution:
    def countSubIslands(self, grid1: List[List[int]], grid2: List[List[int]]) -> int:
        g1, g2 = grid1, grid2
        n, m = len(g1), len(g1[0])

        curr = 2

        dirs = ((0, 1), (1, 0), (-1, 0), (0, -1))

        rec = {}

        def is_good(i, j):
            return 0 <= i < n and 0 <= j < m

        def spread(i, j, g, start=True):
            nonlocal curr

            if g[i][j] != 1:
                return

            g[i][j] = curr
            if g is g2:
                if curr in rec:
                    rec[curr].append((i, j))
                else:
                    rec[curr] = [(i, j)]

            for d1, d2 in dirs:
                x = i + d1
                y = j + d2
                if is_good(x, y):
                    spread(x, y, g, False)

            if start:
                curr += 1

        for i in range(n):
            for j in range(m):
                spread(i, j, g2)

        ans = 0
        for grp in rec:
            corr = None
            broken = False
            g1_done = False
            for i, j in rec[grp]:
                if not g1_done:
                    g1_done = True
                    spread(i, j, g1)
                if corr is None:
                    corr = g1[i][j]
                    if not corr:
                        broken = True
                        break
                if g1[i][j] != corr:
                    broken = True
                    break
            if not broken:
                ans += 1

        # print(*g1, sep="\n")
        # print()
        # print(*g2, sep="\n")
        return ans
50890