Skip to content

1079. Letter Tile Possibilities

Difficulty Topics

Description

You have n  tiles, where each tile has one letter tiles[i] printed on it.

Return the number of possible non-empty sequences of letters you can make using the letters printed on those tiles.

 

Example 1:

Input: tiles = "AAB"
Output: 8
Explanation: The possible sequences are "A", "B", "AA", "AB", "BA", "AAB", "ABA", "BAA".

Example 2:

Input: tiles = "AAABBC"
Output: 188

Example 3:

Input: tiles = "V"
Output: 1

 

Constraints:

  • 1 <= tiles.length <= 7
  • tiles consists of uppercase English letters.

Solution

letter-tile-possibilities.py
class Solution:
    def numTilePossibilities(self, tiles: str) -> int:
        res = set()

        def dfs(curr, word):
            if curr not in res:
                if curr:
                    res.add(curr)

                for i in range(len(word)):
                    dfs(curr + word[i], word[:i] + word[i + 1:])

        dfs('', tiles)

        return len(res)