【BZOJ】1013 球形空间产生器

标签：代数变形   高斯消元   一元n次方程组   bzoj   线性代数   

由于准备要睡觉了没心机检查，结果又一次AC，手感真好...

#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
using namespace std;

const int N=15;
const double eps=1e-5;

int n; double x[N][N];
double a[N][N],sum[N],res[N];

void init(void)
{
	scanf("%d",&n);
	for (int i=1;i<=n+1;i++)
		for (int j=1;j<=n;j++)
			scanf("%lf",&x[i][j]);
	
	for (int i=1;i<=n+1;i++)
		for (int j=1;j<=n;j++)
			sum[i]+=x[i][j]*x[i][j];
	for (int i=1;i<=n;i++)
	{
		for (int j=1;j<=n;j++)
			a[i][j]=x[i+1][j]-x[i][j];
		a[i][n+1]=(sum[i+1]-sum[i])/2;
	}
}

inline int cmp(double i,double j)
{
	if (fabs(i-j)<eps) return 0;
	return i<j?-1:1;
}

inline void swap(int i,int j)
{
	for (int k=1;k<=n+1;k++) a[i][k]+=a[j][k];
	for (int k=1;k<=n+1;k++) a[j][k]=a[i][k]-a[j][k];
	for (int k=1;k<=n+1;k++) a[i][k]-=a[j][k];
}

void gauss(void)
{
	double r;
	for (int i=1;i<=n;i++)
	{
		for (int j=i+1;j<=n;j++)
			if (!cmp(a[i][i],0)||cmp(abs(a[i][i]),abs(a[j][i]))>0) swap(i,j);
		for (int j=i+1;j<=n;j++)
			if (cmp(a[i][j],0))
			{
				r=a[j][i]/a[i][i];
				for (int k=i;k<=n+1;k++) a[j][k]-=a[i][k]*r;
			}
	}
	for (int i=n;i;i--)
	{
		for (int j=i+1;j<=n;j++) a[i][n+1]-=a[i][j]*res[j];
		res[i]=a[i][n+1]/a[i][i];
	}
	
	for (int i=1;i<n;i++) printf("%0.3lf ",res[i]);
	printf("%0.3lf\n",res[n]);
}

int main(void)
{
	init();
	gauss();	
	
	return 0;
}

【BZOJ】1013 球形空间产生器

标签：代数变形   高斯消元   一元n次方程组   bzoj   线性代数   

原文地址：http://blog.csdn.net/u013598409/article/details/46782147