I get WA 1 with calculating distance in this way
for(int i=0;i<len;i++)
            {
                ans+=pow(((int)(buf[i]-'0')),3);
            }
while accepted in this way
 for(int i=0;i<len;i++)
            {
                ans+=(buf[i]-'0')*(buf[i]-'0')*(buf[i]-'0');
            }
WHY?!!!!
Is this a bug on judge or bug in function?!!
the compiler is g++

why not try this

ans+=round(pow(((int)(buf[i]-'0')),3));