高斯消元法【模板】

#include<cstdlib>
#include<cstring>
#include<iostream>
#include<cmath>
using namespace std;
double a[1010][1010],s[1010];
double ans[1010]; 
int n; 
int (){
	scanf("%d",&n);
	for (int i=1;i<=n;++i)
	{
		for (int j=1;j<=n;++j)
			scanf("%lf",&a[i][j]);
		scanf("%lf",&s[i]);
	}
	
	for (int i=1;i<=n;++i)
	{
		if (fabs(a[i][i])<0.00000001)
		{
			printf("No Solutionn");
			return 0;
		}
		
		for (int j=i+1;j<=n;++j)
		{
			double ch=a[j][i]/a[i][i];
			for (int k=i;k<=n;++k)
				a[j][k]-=a[i][k]*ch;
			s[j]-=ch*s[i];
		}
	}
	for (int i=n;i>=1;--i)
	{
		ans[i]=s[i]/a[i][i];
		for (int j=1;j<i;++j)
			s[j]-=a[j][i]*ans[i];
	}
	for (int i=1;i<=n;++i)
		printf("%.2lfn",ans[i]);
		
	return 0;
}