Topics are as follows:
You have a set of
tiles
, where each tile has one lettertiles[i]
printed on it. Return the number of possible non-empty sequences of letters you can make.
Example 1:
Input: "AAB" Output: 8 Explanation: The possible sequences are "A", "B", "AA", "AB", "BA", "AAB", "ABA", "BAA".
Example 2:
Input: "AAABBC" Output: 188
Note:
1 <= tiles.length <= 7
tiles
consists of uppercase English letters.
Problem-solving ideas: the maximum length of tiles is 7, then theoretically up to 7 combinations, this number is very small and can be full array of all the possibilities and then filtered duplicate data!.
code show as below:
class Solution(object): def numTilePossibilities(self, tiles): """ :type tiles: str :rtype: int """ import itertools l = range(len(tiles)) dic = {} for i in range(1,len(l) + 1): for j in itertools.permutations(l, i): v = '' for k in j: v += tiles[k] if v not in dic:dic[v] = 1 return len(dic)