高斯消元 WA on #7 #8

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;
}