46.全排列

  1. class Solution:
  2.     def permute(self, nums: List[int]) -> List[List[int]]:
  3.         def dfs(path,j):
  4.             if(j==len(nums)):
  5.                 ans.append(path[:])   # 如果有pop语句的话，就必须加上[:]，这是为什么呢
  6.                 return 
  7.             for i in range(len(nums)):
  8.                 if nums[i] not in path:
  9.                     path.append(nums[i])
  10.                     dfs(path,j+1)
  11.                     path.pop(-1)  
  12.         ans=[]
  13.         dfs([],0)
  14.         # print(ans)
  15.         return ans

417.太平洋大西洋

  1. class Solution:
  2.     def pacificAtlantic(self, heights: List[List[int]]) -> List[List[int]]:
  3.         def dfs(x,y,point):
  4.             point.append((x,y))
  5.             direction = [[-1,0],[1,0],[0,1],[0,-1]]
  6.             for d in direction:
  7.                 nx=x+d[0]
  8.                 ny=y+d[1]
  9.                 if nx>=0 and ny>=0 and nx<len(heights) and ny<len(heights[0]) and heights[nx][ny]>=heights[x][y] and (nx,ny) not in point:
  10.                     dfs(nx,ny,point)
  11.         point=[]
  12.         for i in range (len(heights[0])):
  13.             dfs(0,i,point)
  14.         for i in range (len(heights)):
  15.             dfs(i,0,point)
  16.         print(point)
  17.         point2=[]
  18.         for i in range (len(heights[0])):
  19.             dfs(len(heights)-1,i,point2)
  20.         for i in range (len(heights)):
  21.             dfs(i,len(heights[0])-1,point2)
  22.         print(point2)
  23.         print(set(point2) & set(point))
  24.         return list(set(point2) & set(point))

为什么每次point都重新开始遍历
image.png