class Solution:
    def pacificAtlantic(self, heights: List[List[int]]) -> List[List[int]]:

        n, m = len(heights), len(heights[0])
        result = []
        p_visited = set()
        a_visited = set()

        def bfs(r, c, visited):
            if r not in range(n) or c not in range(m) or (r, c) in visited:
                return

            from collections import deque
            q = deque()
            visited.add((r, c))
            q.append((r, c))

            while(q):
                (row, col) = q.popleft()
                directions = [(1, 0), (-1, 0), (0, 1), (0, -1)]

                for dr, dc in directions:
                    r = row + dr
                    c = col + dc

                    if r in range(n) and c in range(m) and heights[r][c] >= heights[row][col] and (r, c) not in visited:
                        visited.add((r, c))
                        q.append((r, c))


        for i in range(n):
            bfs(i, 0, p_visited)
            bfs(i, m-1, a_visited)

        for j in range(m):
            bfs(0, j, p_visited)
            bfs(n-1, j, a_visited)

        for r in range(n):
            for c in range(m):
                if (r, c) in p_visited and (r, c) in a_visited:
                    result.append([r, c])

        return result