高斯消斯

#include<bits/stdc++.h>
using namespace std;
const int N=110;
double a[N][N];
const double eps = 1e-8;
int n;
int guess(){
    int c, r;
    for (c = 0, r = 0; c < n; c ++ )
    {
        int t = r;
        for (int i = r; i < n; i ++ )  // 找绝对值最大的行
            if (fabs(a[i][c]) > fabs(a[t][c]))
                t = i;

        if (fabs(a[t][c]) < eps) continue;

        for (int i = c; i <= n; i ++ ) swap(a[t][i], a[r][i]);  // 将绝对值最大的行换到最顶端
        for (int i = n; i >= c; i -- ) a[r][i] /= a[r][c];  // 将当前行的首位变成1
        for (int i = r + 1; i < n; i ++ )  // 用当前行将下面所有的列消成0
            if (fabs(a[i][c]) > eps)
                for (int j = n; j >= c; j -- )
                    a[i][j] -= a[r][j] * a[i][c];

        r ++ ;
    }
    if(r<n){
        for(int i=r;i<n;i++){
            if(fabs(a[i][n])>eps){
                return 2;//无解；
            }
        }
         return 1;
    }
     for (int i = n - 1; i >= 0; i -- )
        for (int j = i + 1; j < n; j ++ )
            a[i][n] -= a[i][j] * a[j][n];
    return 0;
}
int main(){
    cin>>n;
    for(int i=0;i<n;i++){
        for(int j=0;j<n+1;j++) cin>>a[i][j];
    }
     int t = guess();
    if (t == 2) puts("No solution");
    else if (t == 1) puts("Infinite group solutions");
    else
    {
        for (int i = 0; i < n; i ++ )
        {
            if (fabs(a[i][n]) < eps) a[i][n] = 0;  // 去掉输出 -0.00 的情况
            printf("%.2lf\n", a[i][n]);
        }
    }

    return 0;
}