LeetCode 1079 - Letter Tile Possibilities

Recurrsion and BackTracking

Reference -

https://www.youtube.com/watch?v=-3EwpW5UiVo

Code - 
def dfs(hashset,visited, tiles, sb):
	hashset.add(sb)
	for i in range(len(tiles)):
		if not visited[i]:
			visited[i] = True
			sb += tiles[i]
			dfs(hashset, visited, tiles, sb)
			visited[i] = False
			sb = sb[:-1]

hashset = set()
visited = [False]*len(tiles)
dfs(hashset,visited, tiles, "")
print(len(hashset) - 1)
------------------------------------------------------------------------------
Result : print(len(hashset) - 1)