foo.cc: In function 'void change(std::vector<int>)':
foo.cc:22:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0;i < p.size();i++) {
                 ~~^~~~~~~~~~
foo.cc:23:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = i+1;j < p.size();j++) {
                    ~~^~~~~~~~~~
foo.cc: In function 'void add(std::vector<int>)':
foo.cc:32:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  if (p.size()>=lim) return;
      ~~~~~~~~^~~~~
foo.cc:33:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0;i < p.size();i++) {
                 ~~^~~~~~~~~~
foo.cc: In function 'void delt(std::vector<int>)':
foo.cc:74:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0;i < p.size();i++) {
                 ~~^~~~~~~~~~
foo.cc:83:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   } else if (i==p.size()-1) {
              ~^~~~~~~~~~~~
foo.cc: In function 'void bfs()':
foo.cc:104:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (h.k.size()>lim) continue;
       ~~~~~~~~~~^~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)