蒟蒻90分求助

#include <bits/stdc++.h>

using namespace std;

const int N = 55;
const double eps = 1e-6;

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

int main() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    for (int j = 1; j <= n + 1; ++j) {
      cin >> a[i][j];
    }
  }
  for (int i = 1; i <= n; ++i) {  //高斯-约旦消元
    int r = i;
    for (int j = i + 1; j <= n; ++j) {
      if (abs(a[j][i]) > abs(a[r][i])) {
        r = j;
      }
    }
    if (r != i) {
      swap(a[i], a[r]);
    }
    if (abs(a[i][i]) < eps) {
      continue;
    }
    for (int j = 1; j <= n; ++j) {
      if (j == i) {
        continue;
      }
      double p = a[j][i] / a[i][i];
      for (int k = i; k <= n + 1; ++k) {
        a[j][k] -= a[i][k] * p;
      }
    }
    double k = a[i][i];
    for (int j = 1; j <= n + 1; ++j) {
      a[i][j] /= k;
    }
  }
  for (int i = 1; i <= n; ++i) {  //判无穷解、无解
    if (abs(a[i][i]) < eps) {
      if (abs(a[i][n + 1]) > eps) {
        cout << -1;
      } else {
        cout << 0;
      }
      return 0;
    }
  }
  for (int i = 1; i <= n; ++i) {
    cout << 'x' << i << '=';
    printf("%.2lf\n", a[i][n + 1]);
  }
  return 0;
}