bzoj1013: [JSOI2008]球形空间产生器sphere

#include<cstdio>
#include<cstring>
#include<iostream>
#include<cmath>
#include<algorithm>
using namespace std;
#define rep(i,n) for(int i=1;i<=n;i++)
#define REP(i,s,t ) for(int i=s;i<=t;i++)
const int nmax=15;
double A[nmax][nmax],a[nmax],b[nmax];
int n;
void init(){
	scanf("%d",&n);
	rep(i,n) scanf("%lf",&a[i]);
	rep(i,n){
		A[i][n+1]=0;
		rep(j,n) scanf("%lf",&b[j]),A[i][n+1]+=b[j]*b[j]-a[j]*a[j];
		rep(j,n) A[i][j]=(b[j]-a[j])*2.0;
	}
}
void work(){
	rep(i,n) {
		int r=i;
		REP(j,i+1,n) if(fabs(A[j][i])>fabs(A[r][i])) r=j;
		if(r!=i) rep(j,n+1) swap(A[i][j],A[r][j]);
		REP(k,i+1,n){
			double f=A[k][i]/A[i][i];
			REP(j,i,n+1)  A[k][j]-=f*A[i][j];
		}
	}
	for(int i=n;i;i--){
		    REP(j,i+1,n) A[i][n+1]-=A[j][n+1]*A[i][j];
		    A[i][n+1]/=A[i][i];
	    }
	printf("%.3lf",A[1][n+1]);
	REP(i,2,n) printf(" %.3lf",A[i][n+1]);
}
int main(){
	init();work();return 0;
}