Compilare: user.c: In function ‘insert’: user.c:13: warning: implicit declaration of function ‘malloc’ user.c:13: warning: incompatible implicit declaration of built-in function ‘malloc’ user.c: In function ‘del’: user.c:24: warning: implicit declaration of function ‘free’ user.c:24: warning: incompatible implicit declaration of built-in function ‘free’ user.c: In function ‘dijkstra’: user.c:80: warning: incompatible implicit declaration of built-in function ‘malloc’ user.c: In function ‘main’: user.c:128: warning: incompatible implicit declaration of built-in function ‘malloc’ user.c:204: warning: incompatible implicit declaration of built-in function ‘free’ user.c:118: warning: unused variable ‘j’ user.c:120: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:121: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result user.c:123: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:124: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result user.c:137: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result