leetcode 407 接雨水 II

给你一个 m x n 的矩阵，其中的值均为非负整数，代表二维高度图每个单元的高度，请计算图中形状最多能接多少体积的雨水。

该问题与原二维问题的差距还是挺大的
需要借鉴dijkstra算法的思想
python中使用堆队列结构能够较好地实现这个问题
从每次高度最小的点附近开始搜索
判断其附近的点是否能接到雨滴

class Solution:
    def trapRainWater(self, heightMap: List[List[int]]) -> int:
        if not heightMap :return 0
        m,n = len(heightMap),len(heightMap[0])
        if m<3 or n<3:return 0
        state,move = [[False]*n  for _ in range(m)],[(0,1),(0,-1),(1,0),(-1,0)]
        height,res = [],0
        for i in range(1,m-1):
            heapq.heappush(height,(heightMap[i][0],i,0))
            heapq.heappush(height,(heightMap[i][n-1],i,n-1))
        for j in range(1,n-1):
            heapq.heappush(height,(heightMap[0][j],0,j))
            heapq.heappush(height,(heightMap[m-1][j],m-1,j))
        while(height):
            h,x,y = heapq.heappop(height)
            for mo in move:
                xx,yy = x+mo[0],y+mo[1]
                if not 0<xx<m-1 or not 0<yy<n-1 or state[xx][yy]:
                    continue
                state[xx][yy] = True
                res += max(0,h-heightMap[xx][yy])
                heapq.heappush(height,(max(h,heightMap[xx][yy]),xx,yy))
               
        return res