foo.cc: In function 'int main()':
foo.cc:11:29: error: expected ';' before ':' token
    if(a[i]==a[j]) exist[i]++:
                             ^
foo.cc:18:1: error: expected '}' at end of input
 }
 ^

自豪的采用jd5进行评测(github.com/masnn/jd5)