Compilare: user.cpp: In function ‘std::vector<int> intersect(std::vector<int>, std::vector<int>)’: user.cpp:12:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp:12:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp: In function ‘std::vector<int> reunion(std::vector<int>, std::vector<int>)’: user.cpp:28:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp:28:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp:38:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<a.size()) ~^~~~~~~~~ user.cpp:40:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j<b.size()) ~^~~~~~~~~ user.cpp: In function ‘std::vector<int> diff(std::vector<int>, std::vector<int>)’: user.cpp:47:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp:47:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,j=0;i<a.size() && j<b.size();) ~^~~~~~~~~ user.cpp:60:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0,pos=0;i<a.size();++i) ~^~~~~~~~~ user.cpp:62:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pos<sol.size() && sol[pos]==i) ~~~^~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:131:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v.size();++i) ~^~~~~~~~~ user.cpp:134:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i+1==v.size()) ~~~^~~~~~~~~~