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class Solution {
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 public:
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  vector<int> findSubstring(string s, vector<string> &words) {
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    int n = words[0].length();
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    int slen = s.length();
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    int len = slen - n * words.size();
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    vector<int> ans;
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    if (len < 0) return ans;
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    string t;
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    unordered_map<string, int> mp;
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    for (auto i = 0; i < words.size(); ++i) ++mp[words[i]];
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    for (int i = 0; i <= len; ++i) {
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      t = s.substr(i, n);
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      if (mp.find(t) != mp.end()) {
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        unordered_map<string, int> smp;
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        ++smp[t];
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        int flag = 1;
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        for (int j = i + n, k = 1; k < words.size() && j + n <= slen; ++k, j = j + n) {
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          t = s.substr(j, n);
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          if (mp.find(t) != mp.end())
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            ++smp[t];
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          else {
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            flag = 0;
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            break;
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          }
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        }
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        if (flag && smp == mp) ans.push_back(i);
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      }
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    }
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    return ans;
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  }
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};