prepare (1/3): 
finished

make (2/3): 
g++ -g -Wall -O2 -o main graph.cpp
graph.cpp: In function 'void DAG(std::vector<node>)':
graph.cpp:34:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < S.size(); i++){
                    ~~^~~~~~~~~~
graph.cpp:44:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for (int i = 0; i < visiting->next.size(); ++i) {
                         ~~^~~~~~~~~~~~~~~~~~~~~~~
graph.cpp:52:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (s == S.size()) {
         ~~^~~~~~~~~~~
finished

clean (3/3): 
finished

all task finished, build successfully