LeetCode()Substring with Concatenation of All Words 为什么我的超时呢？找不到原因了！！！

class Solution {
public:
vector<int> findSubstring(string s, vector<string>& words) {
map<string,int> coll;
for(auto i:words)
coll[i]++;
vector<int> res;
int len=words[0].size(),sum=words.size();
for(int k=0;k<=s.length()-len*sum;k++)
if(check(s,k,len,sum,coll))
res.push_back(k);
return res;
}
bool check(string s,int start,int len,int sum,map<string,int> coll)
{
for(int i=start;i<=s.length()-len && sum!=0;i+=len)
{
string str=s.substr(i,len);
auto d=coll.find(str);
if(coll[str]>0 && d != coll.end())
{
coll[str]--;
sum--;
}
else
return false;
}
if(sum==0)
return true;
else
return false;
}
};

class Solution {
private:
int wordLen;
public:
vector<int> findSubstring(string S, vector<string> &L) {
unordered_map<string, int>wordTimes;
for(int i = 0; i < L.size(); i++)
wordTimes[L[i]]++;
wordLen = L[0].size();

vector<int> res;
for(int i = 0; i <= (int)(S.size()-L.size()*wordLen); i++)
if(helper(S, i, wordTimes, L.size()))
res.push_back(i);
return res;
}

//判断子串s[index...]的前段是否能由L中的单词组合而成
bool helper(const string &s, int index,
unordered_map<string, int>wordTimes, int wordNum)
{
for(int i = index; wordNum != 0 && i <= (int)s.size()-wordLen; i+=wordLen)
{
string word = s.substr(i, wordLen);
auto ite = wordTimes.find(word);
if(ite != wordTimes.end() && ite->second > 0)
{ite->second--; wordNum--;}
else return false;
}
if(wordNum == 0)return true;
else return false;
}
};