Compilare: main.cpp: In function 'int pair_up()': main.cpp:52:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 52 | for (int i=0; i<singlenode.size()-1; i++) | ~^~~~~~~~~~~~~~~~~~~~ main.cpp:58:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 58 | for (int i=0; i<singlenode.size()-1; i++) | ~^~~~~~~~~~~~~~~~~~~~ main.cpp:66:24: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 66 | for (int i=0; i<singlenode.size()-1; i++) | ~^~~~~~~~~~~~~~~~~~~~ main.cpp:70:1: warning: control reaches end of non-void function [-Wreturn-type] 70 | } | ^