高斯消元板子未过 hack 数据求调

rt.评测记录

看记录是判无解和无限个解的地方出错，但是蒟蒻不知道哪里有问题，求助/bx

#include<bits/stdc++.h>
// #define LOCAL
#define sf scanf
#define pf printf
#define rep(x,y,z) for(int x=y;x<=z;x++)
#define per(x,y,z) for(int x=y;x>=z;x--)
using namespace std;
typedef long long ll;
constexpr int N=55;
double mp[N][N];
double ans[N];
constexpr double base=1e-7;
int n;
int main() {
    #ifdef LOCAL
    freopen("in.txt","r",stdin);
    freopen("my.out","w",stdout);
    #endif
    sf("%d",&n);
    rep(i,1,n) rep(j,1,n+1) sf("%lf",&mp[i][j]);
    int mx=1;
    rep(i,1,n) {
        int r=mx;
        rep(j,mx+1,n) if(fabs(mp[r][i])<fabs(mp[j][i])) r=j;
        if(fabs(mp[r][i])<base) continue;
        if(mx!=r) swap(mp[mx],mp[r]);
        double div=mp[mx][i];
        rep(j,i,n+1) mp[mx][j]/=div;
        rep(j,mx+1,n) {
            div=mp[j][i];
            rep(k,i,n+1) mp[j][k]-=mp[mx][k]*div;
        }
        mx++;
    }
    if(mx<=n) {
        rep(i,mx,n) if(mp[i][n+1]>base) { puts("-1"); return 0; }
        puts("0"); return 0;
    }
    ans[n]=mp[n][n+1];
    per(i,n-1,1) {
        ans[i]=mp[i][n+1];
        rep(j,i+1,n) ans[i]-=mp[i][j]*ans[j];
    }
    rep(i,1,n) pf("x%d=%.2lf\n",i,ans[i]);
}