Compilare: main.cpp: In function 'void add(Trie*, char*)': main.cpp:47:13: warning: NULL used in arithmetic [-Wpointer-arith] if (*s == NULL) { ^~~~ main.cpp: In function 'void solve(Trie*)': main.cpp:77:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < root->sons[i]->dp.size() - 1 && last + j <= k; ++j) ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:83:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int t = 0; t < root->sons[i]->dp.size() && t + j <= k; ++t) ~~^~~~~~~~~~~~~~~~~~~~~~~~~~ main.cpp:93:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (root->dp.size() <= k) ~~~~~~~~~~~~~~~~^~~~ main.cpp: In function 'int main()': main.cpp:119:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cli.in", "r", stdin); ^ main.cpp:121:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("cli.out", "w", stdout); ^ main.cpp:129:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d ", &n, &k); ^ main.cpp:133:19: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%s", s); ^