/in/foo.cc:8:3: error: invalid preprocessing directive #g
 # g=[[[0 for i in range(100)]for i in range(400)]for i in range(20)] 20*400*100的三维数组
   ^
/in/foo.cc:2:1: error: 'dx' does not name a type
 dx=[1,2,2,1,-1,-2,-2,-1]
 ^~
/in/foo.cc:27:13: error: 'f' does not name a type
             f[i][j]=f[i-1][j]+f[i][j-1]
             ^