90pts求助，高斯消元

#include <cmath>
#include <cstdio>
#include <iostream>
#include <algorithm>
#define init signed
#define int double
using namespace std;

init n;
int guass[105][105];

void cheak()
{
    for (init i = 1;i <= n; ++ i)
    {
        if (guass[i][i] == 0)
        {
            if (guass[i][n + 1] == 0)
            {
                cout << 0 << endl;
                exit(0);
            }
            else
            {
                cout << -1 << endl;
                exit(0);
            }
        }
    }
}

init main()
{
    ios::sync_with_stdio(false);
    cin.tie(0) , cout.tie(0);
    cin >> n;
    for (init i = 1;i <= n; ++ i)
    {
        for (init j = 1;j <= n + 1; ++ j)
        {
            cin >> guass[i][j];
        }
    }
    //消元
    for (init i = 1;i <= n; ++ i)
    {
        init maxn_p;
        int maxn = 0;
        for (init j = i;j <= n; ++ j)
        {
            if (fabs(guass[j][i]) >= maxn)
            {
                maxn = fabs(guass[j][i]);
                maxn_p = j;
            }
        }
        for (init j = 1;j <= n + 1; ++ j)
        {
            swap(guass[maxn_p][j] , guass[i][j]);
        }
        if(guass[i][i] == 0)
        {
            continue;
        }
        for (init j = i + 1;j <= n + 1; ++ j)
        {
            guass[i][j] /= guass[i][i];
        }
        for (init j = i + 1;j <= n; ++ j)
        {
            int l = guass[j][i];
            for (init k = 1;k <= n + 1; ++ k)
            {
                guass[j][k] -= l * guass[i][k] ;
            }  
        }

    }
    //回带
    for (init i = n - 1;i >= 1; -- i)
    {
        for (init j = i + 1;j <= n; ++ j)
        {
            guass[i][n + 1] -= guass[i][j] * guass[j][n + 1];
        }
    }
    cheak();
    for (init i = 1;i <= n; ++ i)
    {
        printf("x%d=%.2lf\n", i , guass[i][n + 1]);
    }
    return 0;
}