[LeetCode][Python3] 1079. Letter Tile Possibilities

Problem :

https://leetcode.com/problems/letter-tile-possibilities/

My Solution :

class Solution:

def numTilePossibilities(self, tiles):

def dfs(prefix, remain):

if prefix not in ans:

ans.add(prefix)

for i in range(len(remain)):

dfs(prefix + remain[i], remain[:i] + remain[i+1:])

ans = set()

dfs('', tiles)

return len(ans)-1