高斯约旦消元

试过多个 $eps$ 的值，都是 WA on #7 #8

#include <bits/stdc++.h>
using namespace std;

const int N = 55;
const double eps = 1e-8;

double a[N][N];
int n;

int main()
{
	cin>>n;
	for(int i=1;i<=n;i++)
		for(int j=1;j<=n+1;j++)
			cin>>a[i][j];

	int line = 1;
	for(int i=1;i<=n;i++)
	{
		int t = line;
		for(int j=line+1;j<=n;j++)
			if(fabs(a[t][i]) < fabs(a[j][i])) 
				t = j;
		
		if(a[t][i] == 0) continue;

		for(int j=1;j<=n+1;j++) swap(a[line][j], a[t][j]);

		for(int j=1;j<=n;j++)
			if(line != j)
			{
				double temp = a[j][i] / a[line][i];
				for(int k=i+1;k<=n+1;k++) 
					a[j][k] -= a[line][k] * temp;
			}
		
		line ++;
	}

	if(line <= n)
	{
		while(line <= n)
			if(a[line++][n] != 0) 
			{
				cout<<-1;	
				return 0;
			}
		cout<<0;
		return 0;
	}

	for(int i=1;i<=n;i++)
	 	printf("x%d=%.2lf\n",i,a[i][n+1]/a[i][i]+eps);

	return 0;
}