Bzoj 1013: [JSOI2008] spherical space generator sphere

1#include <iostream>2#include <cstdio>3#include <cmath>4 #defineEPS 1e-65 #defineM 156 using namespacestd;7 DoubleA[m],b[m][m];8 intN;9 intMain ()Ten { Onescanf"%d",&n); A      for(intI=1; i<=n;i++) -scanf"%LF",&a[i]); -      for(intI=1; i<=n;i++) the        for(intj=1; j<=n;j++) -         { -             DoubleT; -scanf"%LF",&t); +b[i][j]=2* (ta[j]); -b[i][n+1]+=t*t-a[j]*A[j]; +         } A      for(intI=1; i<=n;i++) at       { -         intto ; -          for(to=i;to<=n;to++) -           if(b[to][i]!=0) -              Break; -         if(i!=to ) in            for(intj=1; j<=n+1; j + +) - swap (b[i][j],b[to][j]); to         Doublet=B[i][i]; +          for(intj=i;j<=n+1; j + +) -B[i][j]/=T; the          for(intj=1; j<=n;j++) *           if(j!=i) $             {Panax Notoginsengt=B[j][i]; -                  for(intk=1; k<=n+1; k++) theb[j][k]-=t*B[i][k]; +             } A       } the      for(intI=1; i<n;i++) +printf"%.3LF", b[i][n+1]); -printf"%.3lf\n", b[n][n+1]); $     return 0; $}

First assume that the two-dimensional, set the center for (x, y), that (x1-x) ^2+ (y1-y) ^2= (xk-x) ^2+ (yk-y) ^2

So n+1 can construct n equations and then Gaussian elimination. (Gaussian elimination will not look at the code will know)

Bzoj 1013: [JSOI2008] spherical space generator sphere