1 class Solution(object): 2 def maximumMinimumPath(self, A): 3 """ 4 :type A: List[List[int]] 5 :rtype: int 6 """ 7 dire = [[0,1],[1,0],[-1,0],[0,-1]] 8 def check(grid,tar): 9 if grid[0][0] < tar: 10 return False 11 cur = (0,0) 12 seen = set([(0,0)]) 13 def dfs(node): 14 if node == (len(grid)-1,len(grid[0])-1): 15 return True 16 for x,y in dire: 17 if 0<= x+node[0] < len(A) and 0<=y +node[1] < len(A[0]) and grid[node[0]+x][node[1]+y] >= tar and (node[0]+x,node[1]+y) not in seen: 18 seen.add((node[0]+x,node[1]+y)) 19 if dfs((node[0]+x,node[1]+y)): 20 return True 21 return False 22 return dfs(cur) 23 24 L = [] 25 for row in A: 26 L += [i for i in row if i <= A[-1][-1]] 27 L = set(L) 28 L = sorted(L,reverse = True) 29 30 low = 0 31 high = len(L)-1 32 while low < high: 33 idx = (low+high)//2 34 if check(A,L[idx]): 35 high = idx 36 else: 37 low = idx + 1 38 return min(L[high],A[0][0])
我做出来一个TLE的解，只使用了DFS：
1 class Solution: 2 def __init__(self): 3 self.visited = [] 4 self.maxValue = -1 5 6 def dfs(self,A,row,column,i,j,track,direction): 7 if i == row - 1 and j == column - 1: 8 minTrack = min(track[:]) 9 self.maxValue = max(self.maxValue,minTrack) 10 return 11 nextdirct = [] 12 for dirct in direction: 13 x = i + dirct[0] 14 y = j + dirct[1] 15 if x < 0 or x >= row or y < 0 or y >= column: 16 continue 17 if self.visited[x][y] == 1: 18 continue 19 nextdirct.append([A[x][y],x,y]) 20 nextdirct = sorted(nextdirct,key=lambda H:[-H[0]]) 21 if len(nextdirct) > 0: 22 for d in nextdirct: 23 x,y = d[1],d[2] 24 self.visited[x][y] = 1 25 if A[x][y] < self.maxValue: 26 return 27 track.append(A[x][y]) 28 self.dfs(A,row,column,x,y,track,direction) 29 track.pop(-1) 30 self.visited[x][y] = 0 31 32 def maximumMinimumPath(self, A: 'List[List[int]]') -> int: 33 direction = [[0,1],[1,0],[0,-1],[-1,0]] 34 row = len(A) 35 column = len(A[0]) 36 track = [A[0][0]] 37 self.visited = [[0 for _ in range(column)] for _ in range(row)] 38 self.visited[0][0] = 1 39 40 self.dfs(A,row,column,0,0,track,direction) 41 return self.maxValue