# 000139-Word-Break

### Problem

<https://leetcode.com/problems/word-break/description/>

Given a string s and a dictionary of strings wordDict, return true if s can be segmented into a space-separated sequence of one or more dictionary words.

Note that the same word in the dictionary may be reused multiple times in the segmentation.

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

Constraints:

1 <= s.length <= 300 1 <= wordDict.length <= 1000 1 <= wordDict\[i].length <= 20 s and wordDict\[i] consist of only lowercase English letters. All the strings of wordDict are unique.

### Solution

DP problem

```python
class Solution:
    def wordBreak(self, s: str, wordDict: List[str]) -> bool:
        n = len(s)
        dp = [False] * (n+1)
        dp[0] = True
        # max length of a word in the wordDict
        w_max_len = max(map(len, wordDict))
        print(dp)
        print(w_max_len)
        for i in range(1, n+1):
            if dp[i]:
                continue
            for j in range(i-1, max(i-w_max_len-1, -1), -1):
                if dp[j] and s[j:i] in wordDict:
                    dp[i] = True
                    break
            print(dp)
        return dp[n]

# Example "catsanddog", wordDict = ["cats","dog","sand","and","cat"]
# dp = [True, False, False, False, False, False, False, False, False, False]
# w_max_len = 4 (sand) 
# cat -> i = 3, dp[3] = True
# cats -> i = 4 dp[4] = True
# sand -> i = 7 dp[7] = True
# dog -> i = 9 dp[9] = False
# dp = [True, False, False, True, True, False, False, True, False, False] 
# --> dp[9] = False
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://snowan.gitbook.io/study-notes/leetcode/python/000139-word-break.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.