/in/foo.c:4:1: error: unknown type name 'using'
 using namespace std;
 ^~~~~
/in/foo.c:4:17: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'std'
 using namespace std;
                 ^~~
/in/foo.c: In function 'main':
/in/foo.c:17:9: error: expected expression before ':' token
     ios::sync_with_stdio(false);
         ^
/in/foo.c:19:5: error: 'cin' undeclared (first use in this function)
     cin >> n ;
     ^~~
/in/foo.c:19:5: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:22:5: warning: implicit declaration of function 'sort' [-Wimplicit-function-declaration]
     sort(arr + 1, arr + n + 1);//对数据先排序，防止优先队列超时
     ^~~~
/in/foo.c:26:9: error: 'Q' undeclared (first use in this function)
         Q.push(arr[i]) ;//将元素插入队中
         ^
/in/foo.c:17:5: warning: label 'ios' defined but not used [-Wunused-label]
     ios::sync_with_stdio(false);
     ^~~