<p>You are given <code>row x col</code> <code>grid</code> representing a map where <code>grid[i][j] = 1</code> represents&nbsp;land and <code>grid[i][j] = 0</code> represents water.</p>

<p>Grid cells are connected <strong>horizontally/vertically</strong> (not diagonally). The <code>grid</code> is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).</p>

<p>The island doesn&#39;t have &quot;lakes&quot;, meaning the water inside isn&#39;t connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don&#39;t exceed 100. Determine the perimeter of the island.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img src="https://assets.leetcode.com/uploads/2018/10/12/island.png" style="width: 221px; height: 213px;" />
<pre>
<strong>Input:</strong> grid = [[0,1,0,0],[1,1,1,0],[0,1,0,0],[1,1,0,0]]
<strong>Output:</strong> 16
<strong>Explanation:</strong> The perimeter is the 16 yellow stripes in the image above.
</pre>

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

<pre>
<strong>Input:</strong> grid = [[1]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> grid = [[1,0]]
<strong>Output:</strong> 4
</pre>

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

<ul>
	<li><code>row == grid.length</code></li>
	<li><code>col == grid[i].length</code></li>
	<li><code>1 &lt;= row, col &lt;= 100</code></li>
	<li><code>grid[i][j]</code> is <code>0</code> or <code>1</code>.</li>
	<li>There is exactly one island in <code>grid</code>.</li>
</ul>

class Solution:

    def __init__(self):
        self.visited = set()
        self.perim = 0
#
    def findStart(self):        
        for i, list_i in enumerate(self.grid):
            for j, item in enumerate(self.grid[i]):
                if item:
                    #print("first = {}".format((i,j)))
                    return (i, j)
#
    def find_next(self, cur, prev):
#        print(self.visited)
        if cur in self.visited:
#            print(f"{cur=} is already visited")
            return
#        
        self.visited.add(cur)
        i, j  = cur
#
        left  = (i, j-1) if j > 0 else None
#        print(f"{left=}")
        up    = (i-1, j) if i > 0 else None
#        print(f"{up=}")
        right = (i, j+1) if j < self.max_j else None
#        print(f"{right=}")
        down  = (i+1, j) if i < self.max_i else None
#        print(f"{down=}")
#        
        for direction in (left, up, right, down):            
            if not direction or not self.grid[direction[0]][direction[1]]:
                self.perim += 1
            elif direction != prev:
                self.find_next(direction, cur)
 #       
    def islandPerimeter(self, grid: list[list[int]]) -> int:
        self.grid = grid
        self.max_i = len(grid) - 1
        self.max_j = len(grid[0]) - 1                
        self.find_next(self.findStart(), None)
        return self.perim
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