Compilare: user.cpp: In member function ‘PairingHeap::H* PairingHeap::joinPairs(std::vector<PairingHeap::H*>)’: user.cpp:39:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v.size(); i += 2) ~~^~~~~~~~~~ user.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i + 1 < v.size()) newv.push_back(join(v[i], v[i + 1])); ~~~~~~^~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:124:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.in", "r", stdin); ^ user.cpp:125:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("heapuri.out", "w", stdout); ^ user.cpp:129:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &Q); ^ user.cpp:133:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &op); ^ user.cpp:137:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^ user.cpp:143:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &x); ^