foo.cc: In function 'int jj(int*, int, int*, int, int*)':
foo.cc:29:9: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return k;
         ^
foo.cc: In function 'int main()':
foo.cc:27:7: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]
    c[k++]=a[i]; //c[k]=a[i], k++;
      ~^~
foo.cc:23:6: note: 'k' was declared here
  int k;
      ^
foo.cc:23:6: warning: 'k' may be used uninitialized in this function [-Wmaybe-uninitialized]

自豪的采用HydroJudge(https://github.com/hydro-dev/Hydro)进行评测。