Compilare: user.cpp: In function ‘void transpose_matrix(std::vector<std::vector<int> >&)’: user.cpp:18:13: warning: unused variable ‘useless’ [-Wunused-variable] int useless = 1; ^ user.cpp: In function ‘std::vector<std::vector<int> > get_sol(const std::vector<std::vector<int> >&, int)’: user.cpp:84:17: warning: unused variable ‘tes’ [-Wunused-variable] int tes = lg[i][col]; ^ In file included from /usr/include/c++/5/cassert:43:0, from /usr/include/x86_64-linux-gnu/c++/5/bits/stdc++.h:33, from user.cpp:1: user.cpp: In function ‘int Solve(std::vector<std::vector<int> >)’: user.cpp:118:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(lef.size() == N); assert(rig.size() == N); ^ user.cpp:118:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] assert(lef.size() == N); assert(rig.size() == N); ^