foo.c:2:0: warning: ignoring #pragma warning  [-Wunknown-pragmas]
 #pragma warning(disable:4996)
 
foo.c:5:11: error: unknown type name 'subject'
 int Solve(subject s, int n, int r, int x);
           ^~~~~~~
foo.c: In function 'main':
foo.c:11:5: error: unknown type name 'subject'
     subject s = politics;
     ^~~~~~~
foo.c:11:5: note: use 'enum' keyword to refer to the type
foo.c:12:13: warning: implicit declaration of function 'Solve' [-Wimplicit-function-declaration]
     int x = Solve(s, n, 1, 0);
             ^~~~~
foo.c: At top level:
foo.c:17:11: error: unknown type name 'subject'
 int Solve(subject s, int n, int r, int x)//r为排第r门
           ^~~~~~~

自豪的采用jd5进行评测(github.com/masnn/jd5)