Count the Tile Sequences

Medium

You have a set of letter tiles, like in a board game: the letters are given in the string tiles, one letter per tile. Letters may repeat. You lay one or more of the tiles in a row (using each tile at most once) and read off the sequence of letters. How many different non-empty letter sequences can you form? Rows that read the same are counted once, even if they use different tiles.

Example 1

tiles="XYY" → 8

Length 1: X, Y. Length 2: XY, YX, YY. Length 3: XYY, YXY, YYX. That is 8 in total.

Example 2

tiles="MN" → 4

You can make M, N, MN and NM.

Example 3

tiles="ZZZZ" → 4

Constraints

1 ≤ len(tiles) ≤ 7
tiles consists of uppercase English letters

Have you seen this problem in a real interview?

Solved by0

Tried by0

Submissions0

Acceptance—

Topics

Hash Table String Backtracking Counting

Similar problems

Keypad Words Medium Palindromes From a Set of Letters Medium Does the String Fit the Letter Template Medium A Hint for a Digit Guess Medium Characters Grouped by Count Medium

Input

tiles="XYY"

Expected

Run checks the first 3 tests in your browser. Submit checks all 39 tests on the server, hidden ones included.