Eroare de compilare: user.cpp: In function ‘int main()’: user.cpp:92:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k >= sols.size()) g << -1; ^ In file included from /usr/include/c++/4.8/algorithm:62:0, from /usr/include/i386-linux-gnu/c++/4.8/bits/stdc++.h:64, from user.cpp:18: /usr/include/c++/4.8/bits/stl_algo.h: In instantiation of ‘_RandomAccessIterator std::__unguarded_partition(_RandomAccessIterator, _RandomAccessIterator, const _Tp&) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<a_solution*, std::vector<a_solution> >; _Tp = a_solution]’: /usr/include/c++/4.8/bits/stl_algo.h:2307:70: required from ‘_RandomAccessIterator std::__unguarded_partition_pivot(_RandomAccessIterator, _RandomAccessIterator) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<a_solution*, std::vector<a_solution> >]’ /usr/include/c++/4.8/bits/stl_algo.h:2338:54: required from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size) [with _RandomAccessIterator = __gnu_cxx::__normal_iterator<a_solution*, std::vector<a_solution> >; _Size = int]’ /usr/include/c++/4.8/bits/stl_algo.h:5475:36: required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = __gnu_cxx::__normal_iterator<a_solution*, std::vector<a_solution> >]’ user.cpp:85:29: required from here /usr/include/c++/4.8/bits/stl_algo.h:2269:19: error: passing ‘const a_solution’ as ‘this’ argument of ‘bool a_solution::operator<(const a_solution&)’ discards qualifiers [-fpermissive] while (__pivot < *__last) ^