Compilare: main.cpp: In function 'void precompute()': main.cpp:14:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < str.size(); ++i) ~~^~~~~~~~~~~~ main.cpp: In function 'bool no_solution()': main.cpp:20:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (frq[i] * 2 > str.size()) ~~~~~~~~~~~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:50:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < ans.size(); ++i) { ~~^~~~~~~~~~~~ main.cpp:33:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("laundering.in","r",stdin); ^ main.cpp:34:41: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("laundering.out","w",stdout); ^