#1079
Letter Tile Possibilities
medium · verified · 83.5% accepted · 3,137 likes · top 95%
hash table · string · backtracking · counting
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
Solution