![](\"https://assets.leetcode.com/uploads/2021/06/08/waterflow-grid.jpg\")
There is an m x n rectangular island that borders both the Pacific Ocean and Atlantic Ocean. The Pacific Ocean touches the island's left and top edges, and the Atlantic Ocean touches the island's right and bottom edges.
The island is partitioned into a grid of square cells. You are given an m x n integer matrix heights where heights[r][c] represents the height above sea level of the cell at coordinate (r, c).
The island receives a lot of rain, and the rain water can flow to neighboring cells directly north, south, east, and west if the neighboring cell's height is less than or equal to the current cell's height. Water can flow from any cell adjacent to an ocean into the ocean.
\n\nReturn a 2D list of grid coordinates result where result[i] = [ri, ci] denotes that rain water can flow from cell (ri, ci) to both the Pacific and Atlantic oceans.
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Example 1:
\n\n\nInput: heights = [[1,2,2,3,5],[3,2,3,4,4],[2,4,5,3,1],[6,7,1,4,5],[5,1,1,2,4]]\nOutput: [[0,4],[1,3],[1,4],[2,2],[3,0],[3,1],[4,0]]\nExplanation: The following cells can flow to the Pacific and Atlantic oceans, as shown below:\n[0,4]: [0,4] -> Pacific Ocean \n [0,4] -> Atlantic Ocean\n[1,3]: [1,3] -> [0,3] -> Pacific Ocean \n [1,3] -> [1,4] -> Atlantic Ocean\n[1,4]: [1,4] -> [1,3] -> [0,3] -> Pacific Ocean \n [1,4] -> Atlantic Ocean\n[2,2]: [2,2] -> [1,2] -> [0,2] -> Pacific Ocean \n [2,2] -> [2,3] -> [2,4] -> Atlantic Ocean\n[3,0]: [3,0] -> Pacific Ocean \n [3,0] -> [4,0] -> Atlantic Ocean\n[3,1]: [3,1] -> [3,0] -> Pacific Ocean \n [3,1] -> [4,1] -> Atlantic Ocean\n[4,0]: [4,0] -> Pacific Ocean \n [4,0] -> Atlantic Ocean\nNote that there are other possible paths for these cells to flow to the Pacific and Atlantic oceans.\n\n\n
Example 2:
\n\n\nInput: heights = [[1]]\nOutput: [[0,0]]\nExplanation: The water can flow from the only cell to the Pacific and Atlantic oceans.\n\n\n
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Constraints:
\n\nm == heights.lengthn == heights[r].length1 <= m, n <= 2000 <= heights[r][c] <= 105有一个 m × n 的矩形岛屿，与 太平洋 和 大西洋 相邻。 “太平洋” 处于大陆的左边界和上边界，而 “大西洋” 处于大陆的右边界和下边界。
这个岛被分割成一个由若干方形单元格组成的网格。给定一个 m x n 的整数矩阵 heights ， heights[r][c] 表示坐标 (r, c) 上单元格 高于海平面的高度 。
岛上雨水较多，如果相邻单元格的高度 小于或等于 当前单元格的高度，雨水可以直接向北、南、东、西流向相邻单元格。水可以从海洋附近的任何单元格流入海洋。
\n\n返回网格坐标 result 的 2D 列表 ，其中 result[i] = [ri, ci] 表示雨水从单元格 (ri, ci) 流动 既可流向太平洋也可流向大西洋 。
\n\n
示例 1：
\n\n
\n输入: heights = [[1,2,2,3,5],[3,2,3,4,4],[2,4,5,3,1],[6,7,1,4,5],[5,1,1,2,4]]\n输出: [[0,4],[1,3],[1,4],[2,2],[3,0],[3,1],[4,0]]\n\n\n
示例 2：
\n\n\n输入: heights = [[2,1],[1,2]]\n输出: [[0,0],[0,1],[1,0],[1,1]]\n\n\n
\n\n
提示：
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