train.cpp: In function 'bool solve(int, int)':
train.cpp:15:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int k=0;k<g[i].size();k++){
^
train.cpp:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int k=0;k<g[i].size();k++){
^
train.cpp: In function 'bool solve2(int)':
train.cpp:37:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int k=0;k<g[i].size();k++){
^
train.cpp:44:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int k=0;k<g[i].size();k++){
^
train.cpp: In function 'std::vector<int> who_wins(std::vector<int>, std::vector<int>, std::vector<int>, std::vector<int>)':
train.cpp:59:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int i=0;i<u.size();i++) g[u[i]].push_back(v[i]);
^
train.cpp:63:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
for(int j=0;j<g[i].size();j++){
^