This line: tmin = (fabs(dot))/mod;
should read tmin = -dot/mod; Change the rest of the program accordingly. E.g. fabs(dot) < ERR should be -dot <= 0. Also, you often test fabs(sth) < ERR, and this will work as long as there are less than about 10 million flies because then it is the same as testing fabs(sth) == 0. Consider the case of (10^8) - 1 flies at position (0,0,0) standing still (speed = 0) and one fly at position (1,0,0) with speed (-1,0,0). The minimal distance will be 0 at time 1 because then the one moving fly is at the origin, but because the initial distance and the speed are 1/10^8 = 10^-8 which are smaller than 10^7, you will set the minimum distance to 0 but you set the time to 0 too, which is far from the correct answer of 1. You are testing for scale, not for "zeroness", which means you probably put these tests there for the wrong reason. Peter On Wed, Sep 16, 2009 at 8:00 PM, Seedrick <[email protected]> wrote: > > Someone please tell me what is the problem in my code > > #define sq(a) ((a)*(a)) > #define ERR 1e-7 > int main() { > freopen("B-small-attempt11.in","r",stdin); > freopen("B-small-attempt11.out","w",stdout); > int tc,i,j,k,n,a,b,c,va,vb,vc; > double u[3],ap,dot,dmin,tmin,mod; > cin >> tc; > for(i=0;i<tc;i++) { > cin >> n; > vector<double> p(3,0.0); > vector<double> v(3,0.0); > for(j=0;j<n;j++) { > cin >> a >> b >> c >> va >> vb >> vc; > p[0]+=a; > p[1]+=b; > p[2]+=c; > v[0]+=va; > v[1]+=vb; > v[2]+=vc; > } > p[0]=p[0]/n; > p[1]=p[1]/n; > p[2]=p[2]/n; > > v[0]=v[0]/n; > v[1]=v[1]/n; > v[2]=v[2]/n; > > mod = sqrt ( sq(v[0])+sq(v[1])+sq(v[2]) ); > if(mod < ERR ) > { > mod=0.0; > dmin=sqrt (sq(p[0])+sq(p[1])+sq(p[2])); > if(dmin < ERR) > dmin =0.0 ; > printf("Case #%d: %.8lf %.8lf\n",i+1,dmin,mod); > continue; > } > u[0]=v[0]/mod; > u[1]=v[1]/mod; > u[2]=v[2]/mod; > ap=sq(p[0])+sq(p[1])+sq(p[2]); > dot=p[0]*u[0]+p[1]*u[1]+p[2]*u[2]; > if(fabs(dot) < ERR) > { > dmin = sqrt(ap); > tmin=0.0; > } > else > { > dmin= ap-sq(dot); > dmin = sqrt(dmin); > tmin = (fabs(dot))/mod; > } > printf("Case #%d: %.8lf %.8lf\n",i+1,dmin,tmin); > } > return 0; > } > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "google-codejam" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-code?hl=en -~----------~----~----~----~------~----~------~--~---
