leetcode:Substring with Concatenation of All Words

You are given a string, s, and a list of words, words, that are all of the same length. Find all starting indices of substring(s) in s that is a concatenation of each word in wordsexactly once and without any intervening characters.

For example, given:
s: "barfoothefoobarman"
words: ["foo", "bar"]

You should return the indices: [0,9].
(order does not matter).

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class Solution {
    
private:
    bool isConcatenation(string s, map<string, int> &auxMap, int wordLen) {
        map<string, int> curMap;
        
        for (int i=0; i<s.size(); i+=wordLen)
        {
            string curStr = s.substr(i, wordLen);
            
            if (auxMap.find(curStr) == auxMap.end())
                return false;
            
            curMap[curStr]++;
            if (curMap[curStr] > auxMap[curStr]) //超过了也不行
                return false;
        }
        return true;
    }
    
public: //这道题有点像最小匹配窗口那一道，都需要两个map，一个是tamplate map，一个是curMap
    vector<int> findSubstring(string s, vector<string>& words) {
        
        vector<int> retVtr;
        
        if (s.size() == 0 || words.size() == 0)
            return retVtr;
        
        int wordLen = words[0].size();
        int templateLen = wordLen * words.size();
        
        map<string, int> auxMap;
        for (int i=0; i<words.size(); i++) {
            auxMap[words[i]]++;
        }
        
        int curIdx = 0;
        while (curIdx <= (int)s.size()-templateLen)
        {
            if (isConcatenation(s.substr(curIdx, templateLen), auxMap, wordLen))
            {
                retVtr.push_back(curIdx);
            }
            curIdx++;//同时注意这里
        }
        
        return retVtr;
    }
};