fixed code http://ideone.com/wovGYJ

see to //--->> see ... comments !!!

Why do you use VLA (variable length array) ??? — it's extension of GCC, not valid for C++, as know as.

string arr[cities+1]; // cities - is variable, and arr - is variable length array.
vector< pair<int,int>> adjacencylist[cities+1] ;  // adjacencylist also VLA.

//valid for C++
//1. method : dynamic array - std::vector
vector< string > arr(cities + 1);
vector< vector< pair<int, int> > > adjacencylist(cities+1);

//2. method: static array :
string arr[10001]; // 10000 - maximum possible cities number
vector< pair<int, int> > adjacencylist[ 10001]; // 10000 - maximum possible cities number.