Given a non-empty string s and a dictionary wordDict containing a list of non-empty words, determine if s can be segmented into a space-separated sequence of one or more dictionary words.
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 = "leetcode", wordDict = ["leet", "code"] Output: true Explanation: Return true because"leetcode"can be segmented as"leet code".
Example 2:
Input: s = "applepenapple", wordDict = ["apple", "pen"] Output: true Explanation: Return true because"applepenapple"can be segmented as"apple pen apple". Note that you are allowed to reuse a dictionary word.
Example 3:
Input: s = "catsandog", wordDict = ["cats", "dog", "sand", "and", "cat"] Output: false
# TLE solution
class Solution:
def helper(self, s):
if not s: return True
return any(self.helper(s[len(word):]) for word in self.wordDict if s.startswith(word))
def wordBreak(self, s: str, wordDict: List[str]) -> bool:
self.wordDict = wordDict
return self.helper(s)
# Basic DP
class Solution:
def wordBreak(self, s: str, wordDict: List[str]) -> bool:
dp = [False] * len(s)
for i in range(len(s)):
for word in wordDict:
if s[:i+1].endswith(word) and (dp[i-len(word)] or i-len(word) == -1):
dp[i] = True
return dp[-1]
# Advanced DP
class Solution:
def wordBreak(self, s: str, wordDict: List[str]) -> bool:
dp = [True]
for i in range(1, len(s)+1):
dp += any(dp[j] and s[j:i] in wordDict for j in range(i)),
return dp[-1]