[LC] 139. Word Break

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

Time: O(N^3)
Space: O(N)

 1 class Solution:
 2     def wordBreak(self, s: str, wordDict: List[str]) -> bool:
 3         can_break = [False] * (len(s) + 1)
 4         
 5         for i in range(1, len(s) + 1):
 6             if s[:i] in wordDict:
 7                 can_break[i] = True
 8                 continue
 9             for j in range(1, i):
10                 if can_break[j] and s[j: i] in wordDict:
11                     can_break[i] = True
12                     break
13         return can_break[len(s)]
14