Compilare: user.cpp:9:0: warning: "INFINITY" redefined [enabled by default] #define INFINITY ((1 << 31) - 1) ^ In file included from /usr/include/math.h:40:0, from /usr/include/c++/4.8/cmath:44, from /usr/include/c++/4.8/random:38, from /usr/include/c++/4.8/bits/stl_algo.h:65, from /usr/include/c++/4.8/algorithm:62, from user.cpp:3: /usr/include/i386-linux-gnu/bits/inf.h:27:0: note: this is the location of the previous definition # define INFINITY (__builtin_inff()) ^ user.cpp: In function ‘int main()’: user.cpp:9:31: warning: integer overflow in expression [-Woverflow] #define INFINITY ((1 << 31) - 1) ^ user.cpp:26:51: note: in expansion of macro ‘INFINITY’ Distance.push_back(vector < int > (V + 1, INFINITY)); ^ user.cpp:13:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("royfloyd.in", "r", stdin); ^ user.cpp:14:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("royfloyd.out", "w", stdout); ^ user.cpp:21:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &V); ^ user.cpp:33:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &M[i][j]); ^