两道Leetcode比赛题 (第140届)

class Solution:
    def findOcurrences(self, text: str, first: str, second: str) -> List[str]:
        if text is None:
            return []
        words = text.split(" ")
        print(words)
        if len(words)<=2:
            return []
        print('here')
        seqs=[]
        seqs = [words[i+2] for i in range(len(words)-2) if words[i] == first and words[i+1] == second]
        return seqs

"A", "B", "AA", "AB", "BA", "AAB", "ABA", "BAA"

from collections import Counter

class Solution:
    def numTilePossibilities(self, tiles: str) -> int:
        if len(tiles) == 0:
            return 0
        
        dt = dict(Counter(tiles))
        
        return self.dfs(dt);
    
    def dfs(self,dt):
        sum = 0
        for k,v in dt.items():
            if v == 0:
                continue
            
            sum += 1    
            dt[k] -= 1
            sum += self.dfs(dt)
            dt[k] += 1
            
        return sum