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:
[]
class Solution(object):
def wordBreak(self, s, wordDict):
return self.dfs(s, set(wordDict), 0, {})
def dfs(self, s, wordDict, start, memo):
if start >= len(s): return [""]
if start in memo: return memo[start]
ans = []
for i in range(start+1, len(s)+1):
w = s[start:i]
if w in wordDict:
ans += [" ".join([w, x]) if x else w for x in self.dfs(s, wordDict, i, memo)]
memo[start] = ans
return ans