Bzoj 1013 JSOI2008 Spherical space Generator sphere Gaussian elimination element

Topic: Given n-dimensional space under the n+1 point, the N-point of the spherical sphere

I've been trying for a long time. Simulated annealing 0.0 still not AC 0.0

Today, digging the dung wall to learn the Gaussian elimination yuan ...

We set the sphere to X (x1,x2,..., xn)

Suppose there are two points a (a1,a2,..., an) and B (B1,b2,..., bn)

Then we can get two equations.

(X1-A1) ^2+ (X2-A2) ^2+...+ (Xn-an) ^2=r^2

(X1-B1) ^2+ (X2-B2) ^2+...+ (xn-bn) ^2=r^2

These equations are all two times and cannot be applied to Gaussian elimination

But we can do some processing. Subtract the above two equations to get a

(A1-B1) x1+ (A2-B2) x2+...+ (an-bn) xn=[(a1^2-b1^2) + (a2^2-b2^2) +...+ (an^2-bn^2)]/2

R is eliminated, n equations, n unknowns can be applied to Gaussian elimination template

has been tangled in the simulated annealing why not cut off 0.0

#include <cmath> #include <cstdio> #include <cstring> #include <iostream> #include < Algorithm> #define M 20using namespace Std;int n;double pos[m],a[m][m],ans[m];int main () {int i,j,k;cin>>n;for ( i=1;i<=n;i++) scanf ("%lf", &pos[i]), for (i=1;i<=n;i++) {double temp[m];for (j=1;j<=n;j++) {scanf ("%lf", &TEMP[J]); a[i][j]=pos[j]-temp[j];a[i][n+1]+=pos[j]*pos[j]-temp[j]*temp[j];} a[i][n+1]/=2;} for (i=1;i<=n;i++) {k=0;for (j=i;j<=n;j++) if (Fabs (A[j][i]) >fabs (A[k][i])) k=j;for (j=1;j<=n+1;j++) Swap ( A[I][J],A[K][J]); for (j=i+1;j<=n;j++) {double temp=-a[j][i]/a[i][i];for (k=i;k<=n+1;k++) a[j][k]+=a[i][k]* temp;}} for (i=n;i;i--) {for (j=n;j>i;j--) a[i][n+1]-=a[i][j]*ans[j];ans[i]=a[i][n+1]/a[i][i];} for (i=1;i<=n;i++) printf ("%.3lf%c", ans[i],i==n? ' \ n ': ');}

Bzoj 1013 JSOI2008 Spherical space Generator sphere Gaussian elimination element