Compilare: user.c: In function ‘bfs’: user.c:14:3: warning: implicit declaration of function ‘memset’ [-Wimplicit-function-declaration] memset(viz, 0, sizeof viz); ^ user.c:14:3: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] user.c: In function ‘main’: user.c:51:3: warning: incompatible implicit declaration of built-in function ‘memset’ [enabled by default] memset(ult, -1, sizeof ult); ^ user.c:48:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &n); ^ user.c:63:11: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d%d", &x, &y); ^