View Compilation Error

0_0_30967966_375.cpp:22:1: error: 'vector' does not name a type
 vector<int> F[256];
 ^
0_0_30967966_375.cpp: In function 'int main()':
0_0_30967966_375.cpp:48:43: error: 'F' was not declared in this scope
         for (char c = 'a'; c <= 'z'; ++c) F[c].clear();
                                           ^
0_0_30967966_375.cpp:49:46: error: 'F' was not declared in this scope
         for (int i = 0; i < str.size(); ++i) F[str[i]].push_back(i);
                                              ^
0_0_30967966_375.cpp:54:27: error: 'F' was not declared in this scope
             for (auto p : F[fst[i]]) {
                           ^