蒟蒻90pts求助 , 卡在 #9 了

#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const double eps=1e-7;
const int N=110;
int T,n;
double a[N][N],ans[N],b[N];
double F(double A)
{
    if(A<0) return -A;
    return A;
}
int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=n;j++)
            scanf("%lf",&a[i][j]);
        scanf("%lf",&b[i]);
    }
    for(int i=1;i<=n;i++)
    {
        int Max=i;
        for(int j=i+1;j<=n;j++)
            if(F(a[j][i])>F(a[Max][i])) Max=j;
        for(int l=i;l<=n;l++) swap(a[i][l],a[Max][l]);
        swap(b[i],b[Max]);
        if(F(a[i][i])<eps) continue;
        for(int j=i+1;j<=n;j++)
        {
            double k=a[j][i]/a[i][i];
            for(int l=i;l<=n;l++)
                a[j][l]-=k*a[i][l];
            b[j]-=k*b[i];
        }
    }
    for(int i=n;i>=1;i--)
    {
        for(int j=n;j>i;j--)
            b[i]-=ans[j]*a[i][j];
        ans[i]=b[i]/a[i][i];
    }
    for(int i=1;i<=n;i++)
    {
        if(F(a[i][i])<eps)
        {
            if(!b[i]) {printf("0");return 0;}
            else T=1;
        }
    }
    if(T) {printf("-1");return 0;}
    for(int i=1;i<=n;i++) 
    {
        if(ans[i]==-0) ans[i]=0;
        printf("x%d=%.2lf\n",i,ans[i]);
    }
    return 0;
}