/in/foo.cc:6:16: error: 'int time [21][21]' redeclared as different kind of symbol
 int time[21][21];       //  记录 i 号工件第 j 个工序所用的时间
                ^
In file included from /usr/include/c++/6/ctime:42:0,
                 from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:49,
                 from /in/foo.cc:1:
/usr/include/time.h:192:15: note: previous declaration 'time_t time(time_t*)'
 extern time_t time (time_t *__timer) __THROW;
               ^~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:20:31: warning: pointer to a function used in arithmetic [-Wpointer-arith]
             scanf("%d",&time[i][j]);
                               ^
/in/foo.cc:20:34: warning: pointer to a function used in arithmetic [-Wpointer-arith]
             scanf("%d",&time[i][j]);
                                  ^
/in/foo.cc:20:35: warning: format '%d' expects argument of type 'int*', but argument 2 has type 'time_t (*)(time_t*) throw () {aka long int (*)(long int*) throw ()}' [-Wformat=]
             scanf("%d",&time[i][j]);
                                   ^
/in/foo.cc:30:30: warning: pointer to a function used in arithmetic [-Wpointer-arith]
             if(s==time[num[i]][work[num[i]]])    //  机器表示：我闲着！！
                              ^
/in/foo.cc:30:44: warning: pointer to a function used in arithmetic [-Wpointer-arith]
             if(s==time[num[i]][work[num[i]]])    //  机器表示：我闲着！！
                                            ^
/in/foo.cc:30:44: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]