Trie-648. Replace Words

In English, we have a concept called root, which can be followed by some other words to form another longer word - let's call this word successor. For example, the root an, followed by other, which can form another word another.

Now, given a dictionary consisting of many roots and a sentence. You need to replace all the successor in the sentence with the root forming it. If a successor has many roots can form it, replace it with the root with the shortest length.

You need to output the sentence after the replacement.

Example 1:

Input: dict = ["cat", "bat", "rat"]
sentence = "the cattle was rattled by the battery"
Output: "the cat was rat by the bat"

Note:

1. The input will only have lower-case letters.
2. 1 <= dict words number <= 1000 
3. 1 <= sentence words number <= 1000 
4. 1 <= root length <= 100 
5. 1 <= sentence words length <= 1000

class Solution {
public:
    string replaceWords(vector<string>& dict, string sentence) {
        set<string> myDict;
        for(int i=0;i<dict.size();i++)
            myDict.insert(dict[i]);
        vector<string> mySentence;
        for(int i=0,j=0;i<sentence.size() && j<=sentence.size();j++)//把字符串分成单词
        {
            if(sentence[j]==' ' || j==sentence.size())
            {
                mySentence.push_back(sentence.substr(i,j-i));
                i=j+1;
            }
        }
        string res="";
        for(int i=0;i<mySentence.size();i++)
        {           
            for(int j=0;j<mySentence[i].size();j++)
            {
                if(myDict.find(mySentence[i].substr(0,j+1)) != myDict.end())
                {
                    mySentence[i]=mySentence[i].substr(0,j+1);
                    break;
                }
            }
            res+=(mySentence[i]+" ");
        }
        return res.substr(0,res.size()-1);
    }
};