1078. Bigram 分词 pboost

给出第一个词 first 和第二个词 second，考虑在某些文本 text 中可能以 "first second third" 形式出现的情况，其中 second 紧随 first 出现，third 紧随 second 出现。

对于每种这样的情况，将第三个词 "third" 添加到答案中，并返回答案。

案例1：

输入：text = "alice is a good girl she is a good student", first = "a", second = "good"
输出：["girl","student"]

案例2：

输入：text = "we will we will rock you", first = "we", second = "will"
输出：["we","rock"]

/*
这是我的代码，和大神们的比起来我这个比较中规中举，但是运行部分案例时出错了，报错原因是数组下标溢出了，有知道的大神们麻烦留言，谢谢
*/
class Solution {
public:
    vector<string> findOcurrences(string text, string first, string second) {
        vector<string> result;
        int length = text.length();
        for(int i = 0;i < length;i++)
        {
            string subFirst = "";
            while(text[i] != ' ' && text[i] != '\n' && i < length)
            {
                subFirst += text[i];
                i++;
            }
            cout << subFirst << endl;
           if(subFirst == first)
           {
                int lenSecondString = second.length();
                if(i+lenSecondString < length && i+1 < length)
                {
                    string subSecond = text.substr(i+1, lenSecondString);
                    if(subSecond == second)
                    {
                        int j = i+2+lenSecondString;
                        string subThird = "";
                        while(text[j] != ' ' && text[j] != '\n' && j < length)
                        {
                            subThird += text[j];
                            j++;
                        }
                        result.push_back(subThird);
                    }
                }
           }
        }
        return result;
    }
};

请看大神们的正确解答：

class Solution {
public:
    vector<string> findOcurrences(string text, string first, string second) {
        vector<string> result;
        istringstream ss(text); 
        string subFirstString = "";
        string subSecondString = "";
        string curString = "";

        while(ss>>curString) 
        {
            //ss会把内容自动匹配到和curString类型相同的内容，这里就是string，就没有什么异样了，空格会作为匹配内容的结束标识
            if(subFirstString == first && subSecondString==second)
            {
                result.push_back(curString);
            }
            subFirstString = subSecondString;
            subSecondString = curString;
        }
        return result;
    }
};