Compilare: main.c: In function 'main': main.c:54:15: warning: implicit declaration of function 'malloc' [-Wimplicit-function-declaration] int* roots = malloc(sizeof(int) * (n + 1)); ^~~~~~ main.c:54:15: warning: incompatible implicit declaration of built-in function 'malloc' main.c:54:15: note: include '<stdlib.h>' or provide a declaration of 'malloc' main.c:63:2: warning: implicit declaration of function 'memset' [-Wimplicit-function-declaration] memset(layers, 0, sizeof(int) * (n + 1)); ^~~~~~ main.c:63:2: warning: incompatible implicit declaration of built-in function 'memset' main.c:63:2: note: include '<string.h>' or provide a declaration of 'memset' main.c:90:2: warning: implicit declaration of function 'free' [-Wimplicit-function-declaration] free(isRoot); ^~~~ main.c:90:2: warning: incompatible implicit declaration of built-in function 'free' main.c:90:2: note: include '<stdlib.h>' or provide a declaration of 'free' main.c:52:2: warning: ignoring return value of 'fscanf', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d", &n, &m); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:69:3: warning: ignoring return value of 'fscanf', declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d", &node1, &node2); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~