def findDistinctIslandsBit(self, matrix):
        if not matrix or not matrix[0]:
            return None
        # iterate over the matrix finding islands
        # dfs the island shifting the islands "code" based on the traversal
        # add the code int to a set, then return the size of the set
        # will use explicit stack dfs (for no particular reason)
        def dfsIsland(rowStart, colStart):
            code = 0
            stack = [(rowStart, colStart)]
            while stack:
                i, j = stack.pop()
                code <<= 1
                if not (0 <= i < n) or not (0 <= j < m):
                    continue
                code += matrix[i][j]
                if matrix[i][j]:
                    for diff in [-1, 1]:
                        stack.append((i + diff, j))
                        stack.append((i, j + diff))
                    matrix[i][j] = 0
            return code
        
        n = len(matrix)
        m = len(matrix[0])
        islands = set()
        for i in range(n):
            for j in range(m):
                if matrix[i][j]:
                    islandCode = dfsIsland(i, j)
                    islands.add(islandCode)
        return len(islands)