问题描述：

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

For example, given:
S: "barfoothefoobarman"
L: ["foo", "bar"]

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

易错点：不要默认L中的词是不同的。

代码：

vector<int> findSubstring(string S, vector<string> &L) {  C++
        vector<int> result;
        int size = L.size();
        if(size ==0 || S.size() ==0)
            return result;
            
        int len = L[0].size();
        if(S.size() < len*size)
            return result;
            
        map<string,int> myMap;
        for(int i=0; i<L.size(); i++)
            myMap[L[i]]++;
        for(int i=0; i<=S.size()-len*size; i++){
            map<string,int> tempmap;
            int end = i+len*size;
            for(int j=i; j<end; j = j+len){
                string temp = S.substr(j,len);
                if(myMap.count(temp) !=0)
                    tempmap[temp]++;
                else
                    break;
            }
            if(tempmap.size() == myMap.size()){
                bool isSame = true;
                for(map<string,int>::iterator myMap_iter=myMap.begin(); myMap_iter!=myMap.end();myMap_iter++){
                    string key = myMap_iter->first ;
                    if(myMap[key]!=tempmap[key]){
                        isSame=false;
                        break;
                    }
                }
                if(isSame)
                    result.push_back(i);
                
            }
        }
        return result;
    }

[leetcode] 30 Substring with Concatenation of All Words