Seawolf 发表于 2020-7-31 03:32:40

Leetcode 140. Word Break II

Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, add spaces in s to construct a sentence where each word is a valid dictionary word. Return all such possible sentences.

Note:

The same word in the dictionary may be reused multiple times in the segmentation.
You may assume the dictionary does not contain duplicate words.
Example 1:

Input:
s = "catsanddog"
wordDict = ["cat", "cats", "and", "sand", "dog"]
Output:
[
"cats and dog",
"cat sand dog"
]
Example 2:

Input:
s = "pineapplepenapple"
wordDict = ["apple", "pen", "applepen", "pine", "pineapple"]
Output:
[
"pine apple pen apple",
"pineapple pen apple",
"pine applepen apple"
]
Explanation: Note that you are allowed to reuse a dictionary word.
Example 3:

Input:
s = "catsandog"
wordDict = ["cats", "dog", "sand", "and", "cat"]
Output:
[]

给定一个非空字符串 s 和一个包含非空单词列表的字典 wordDict,在字符串中增加空格来构建一个句子,使得句子中所有的单词都在词典中。返回所有这些可能的句子。

说明:

分隔时可以重复使用字典中的单词。
你可以假设字典中没有重复的单词。
示例 1:

输入:
s = "catsanddog"
wordDict = ["cat", "cats", "and", "sand", "dog"]
输出:
[
"cats and dog",
"cat sand dog"
]
示例 2:

输入:
s = "pineapplepenapple"
wordDict = ["apple", "pen", "applepen", "pine", "pineapple"]
输出:
[
"pine apple pen apple",
"pineapple pen apple",
"pine applepen apple"
]
解释: 注意你可以重复使用字典中的单词。
示例:

输入:
s = "catsandog"
wordDict = ["cats", "dog", "sand", "and", "cat"]
输出:
[]

class Solution:
    def wordBreak(self, s: str, wordDict: List) -> List:
      dic = set(wordDict)
      hashmap = {}
      return self.helper(s, dic, hashmap)
   
    def add(sefl, answers: List, string: str) -> List:
      result = []
      for answer in answers:
            result.append(answer + " " + string)
      return result
   
    def helper(self, s: str, dic: List, hashmap) -> List:
      if s in hashmap:
            return hashmap
      ans = []
      if s in dic:
            ans.append(s)
      for i in range(1, len(s)):
            right = s
            if right not in dic: continue
            left = s[:i]
            left_list = self.add(self.helper(left, dic, hashmap), right)
            ans = ans + left_list
      hashmap = ans
      return hashmap
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