rt,程序1挂了，程序2把程序1的break删了就过了

#include<iostream>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<ctime>
#include<climits>
#include<vector>
//#include<bits/stdc++.h>
#define eps (1e-7)
using namespace std;
int n;
double mat[503][503];
void print(){
	printf("*******\n");
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n+1;j++){
			if(mat[i][j]>eps) cout<<mat[i][j]<<" ";
			else cout<<"0 ";
		}
		cout<<endl;
	}
	printf("*******\n");
}
int gauss(){
	for(int j=1;j<=n;j++){
		for(int i=j;i<=n;i++){
			if(fabs(mat[i][j])>eps){
				for(int k=1;k<=n+1;k++){
					swap(mat[i][k],mat[j][k]);
				}
				break;
			}
		}
		//print();
		if(fabs(mat[j][j])<=eps) continue;
		for(int i=1;i<=n;i++){
			if(i==j) continue;
			double rate=mat[i][j]/mat[j][j];
			for(int k=1;k<=n+1;k++){
				mat[i][k]-=rate*mat[j][k];
			}
		}
	}
	//print();
	for(int i=1;i<=n;i++){
		bool f=1;
		for(int j=1;j<=n;j++){
			if(fabs(mat[i][j])>eps){
				f=0;
				break;
			}
		}
		if(f&&fabs(mat[i][n+1])>eps) return -1;
	}
	for(int i=1;i<=n;i++){
		if(fabs(mat[i][i])<=eps&&fabs(mat[i][n+1])<=eps) return 0;
	}
	return 1;
}
int main()
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	//ios::sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n+1;j++){
			cin>>mat[i][j];
		}
	}
	int res=gauss();
	if(res!=1){
		cout<<res;
		return 0;
	}
	//print();
	/*bool no=0,inf=0;
	for(int i=1;i<=n;i++){
		int j=1;
        while(fabs(mat[i][j])<=eps&&j<=n+1) j++;
        if(j>n+1) inf=1;
        if(j==n+1) no=1;
	}
	if(no){
		printf("-1");
		return 0;
	}
	if(inf){
		printf("0");
		return 0;
	}*/
	for(int i=1;i<=n;i++){
		if(fabs(mat[i][n+1]/mat[i][i])<=eps){
			printf("x%d=0.00\n",i);
		}
		printf("x%d=%.2f\n",i,mat[i][n+1]/mat[i][i]);
	}
    return 0;
}

#include<iostream>
#include<cmath>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<cstdlib>
#include<stack>
#include<queue>
#include<set>
#include<map>
#include<ctime>
#include<climits>
#include<vector>
//#include<bits/stdc++.h>
#define eps (1e-7)
using namespace std;
int n;
double mat[503][503];
void print(){
	printf("*******\n");
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n+1;j++){
			if(mat[i][j]>eps) cout<<mat[i][j]<<" ";
			else cout<<"0 ";
		}
		cout<<endl;
	}
	printf("*******\n");
}
int gauss(){
	for(int j=1;j<=n;j++){
		for(int i=j;i<=n;i++){
			if(fabs(mat[i][j])>eps){
				for(int k=1;k<=n+1;k++){
					swap(mat[i][k],mat[j][k]);
				}
			}
		}
		//print();
		if(fabs(mat[j][j])<=eps) continue;
		for(int i=1;i<=n;i++){
			if(i==j) continue;
			double rate=mat[i][j]/mat[j][j];
			for(int k=1;k<=n+1;k++){
				mat[i][k]-=rate*mat[j][k];
			}
		}
	}
	//print();
	for(int i=1;i<=n;i++){
		bool f=1;
		for(int j=1;j<=n;j++){
			if(fabs(mat[i][j])>eps){
				f=0;
				break;
			}
		}
		if(f&&fabs(mat[i][n+1])>eps) return -1;
	}
	for(int i=1;i<=n;i++){
		if(fabs(mat[i][i])<=eps&&fabs(mat[i][n+1])<=eps) return 0;
	}
	return 1;
}
int main()
{
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	//ios::sync_with_stdio(0);
	cin>>n;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=n+1;j++){
			cin>>mat[i][j];
		}
	}
	int res=gauss();
	if(res!=1){
		cout<<res;
		return 0;
	}
	//print();
	/*bool no=0,inf=0;
	for(int i=1;i<=n;i++){
		int j=1;
        while(fabs(mat[i][j])<=eps&&j<=n+1) j++;
        if(j>n+1) inf=1;
        if(j==n+1) no=1;
	}
	if(no){
		printf("-1");
		return 0;
	}
	if(inf){
		printf("0");
		return 0;
	}*/
	for(int i=1;i<=n;i++){
		if(fabs(mat[i][n+1]/mat[i][i])<=eps){
			printf("x%d=0.00\n",i);
		}
		printf("x%d=%.2f\n",i,mat[i][n+1]/mat[i][i]);
	}
    return 0;
}