407. Trapping Rain Water II
Hard
Description
Given an m x n
integer matrix heightMap
representing the height of each unit cell in a 2D elevation map, return the volume of water it can trap after raining.
Example 1:
Input: heightMap = [[1,4,3,1,3,2],[3,2,1,3,2,4],[2,3,3,2,3,1]]
Output: 4
Explanation: After the rain, water is trapped between the blocks.
We have two small ponds 1 and 3 units trapped.
The total volume of water trapped is 4.
Example 2:
Constraints:
m == heightMap.length
n == heightMap[i].length
1 <= m, n <= 200
0 <= heightMap[i][j] <= 2 * 104
Solutions