foo.cc: In function 'bool run(int)':
foo.cc:4:11: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
  if(n%4==0&&n%100!=0||n%400==0)return true;
     ~~~~~~^~~~~~~~~~

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