778-Swim-in-Rising-Water.py

class Solution:
    def swimInWater(self, grid: List[List[int]]) -> int:
        N = len(grid)
        visit = set()
        minH = [[grid[0][0], 0, 0]] # (time/max-height, r, c)
        directions = [[0, 1], [0, -1], [1, 0], [-1 ,0]]
        
        visit.add((0, 0))
        while minH:
            t, r, c = heapq.heappop(minH)
            if r == N - 1 and c == N - 1:
                return t
            for dr, dc in directions:
                neiR, neiC = r + dr, c + dc
                if (neiR < 0 or neiC < 0 or 
                    neiR == N or neiC == N or
                    (neiR, neiC) in visit):
                    continue
                visit.add((neiR, neiC))
                heapq.heappush(minH, [max(t, grid[neiR][neiC]), neiR, neiC])