1079. Letter Tile Possibilities

Problem Link

Description

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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

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Python3

class Solution:
    def numTilePossibilities(self, tiles: str) -> int:
        N = len(tiles)
        seen = set()
 
        def go(curr, mask):
            if curr != "":
                seen.add(curr)
            
            for i in range(N):
                if mask & (1 << i) == 0:
                    go(curr + tiles[i], mask | (1 << i))
 
        go("", 0)
 
        return len(seen)

Python

class Solution(object):
    def numTilePossibilities(self, tiles):
        s = "".join(set(tiles))
        ans = [] 
 
        for char in s:
            ans.append(char)    
 
        for elem in ans:
            temp = elem
 
            for char in s:
                temp += char
                if temp.count(char)<=tiles.count(char): 
                    ans.append(temp)
                temp = elem
                
        return len(set(ans))