139. 单词拆分 代码思路 class Solution: def wordBreak(self, s: str, wordDict: List[str]) -> bool: ss = set(wordDict) n = len(s) f = [False] * (n + 10) f[0] = True for i in range(1, n + 1): j = i while j >= 1 and not f[i]: sub = s[j - 1:i] if sub in ss: f[i] = f[j - 1] j -= 1 return f[n]