leetcode-139 Word Break

139. Word Break

Description

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:

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Input: s = "leetcode", wordDict = ["leet", "code"]
Output: true
Explanation: Return true because "leetcode" can be segmented as "leet code".

Example 2:

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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:

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

Analyse

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int startsWith(string s, string sub){
    return s.find(sub)==0?1:0;
}

bool wordBreak(string s, vector<string>& wordDict) {
    bool result = false;
    for(int i = 0; i < wordDict.size(); i++) {
        if (s == wordDict[i]) {
            return true;
        }
        else if(startsWith(s, wordDict[i])) {
            result = wordBreak(s.substr(wordDict[i].length(), s.length() - wordDict[i].length()), wordDict);
            if (result) {
                return true;
            }
        }

        continue;
    }

    return result;
}