Compilare: main.cpp: In member function 'void Heap::down(int)': main.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] childIndex < heap.size(); ~~~~~~~~~~~^~~~~~~~~~~~~ main.cpp:33:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (childIndex + 1 < heap.size() && cost[heap[childIndex]] > cost[heap[childIndex + 1]]) ~~~~~~~~~~~~~~~^~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:96:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i < cost.size(); ++i) ~~^~~~~~~~~~~~~