prepare (1/3): 
finished

make (2/3): 
g++ -g -Wall -O2 -o main.o -c main.cpp 
g++ -g -Wall -O2 -o shortest_path.o -c shortest_path.cpp 
g++ -g -Wall -O2 -o main main.o shortest_path.o
finished

clean (3/3): 
finished

all task finished, build successfully