prepare (1/3): 
finished

make (2/3): 
g++ -g -Wall -o main.o -c main.cpp  -std=c++11 -O2
g++ -g -Wall -o graph.o -c graph.cpp  -std=c++11 -O2
graph.cpp: In static member function 'static std::pair<int, int> graph::find_min_key(const std::map<int, double>&)':
graph.cpp:71:39: warning: 'min' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return pair<int, int>(min_key, min);
                                       ^
g++ -g -Wall -o main main.o graph.o
rm -f main.o graph.o
finished

clean (3/3): 
finished

all task finished, build successfully