#4 WA（高斯——约旦）

out：-1 ac：0

#include <bits/stdc++.h>
using namespace std;
double A[55][55];
int n;
int main(){
    scanf("%d",&n);
    for(int i=1;i<=n;++i)
        for(int j=1;j<=n+1;++j)
            scanf("%lf",&A[i][j]);
    for(int i=1; i<=n; ++i) {
        int max = i;
        for(int j=i+1; j<=n; ++j)if(fabs(A[j][i])>fabs(A[max][i]))max = j;
        for(int j=1; j<=n+1; ++j)swap(A[i][j],A[max][j]); 
        if(!A[i][i])continue;
        for(int j=1; j<=n; ++j)
            if(j!=i)
                for(int k=i+1; k<=n+1; ++k)
                    A[j][k] -= A[i][k]*A[j][i]/A[i][i];
    }for(int i=1;i<=n;++i)if(!A[i][i]&&!A[i][n+1]){printf("0");return 0;}
    for(int i=1;i<=n;++i)if(!A[i][i]&&A[i][n+1]){printf("-1");return 0;}

    for(int i=1;i<=n;++i)printf("x%d=%.2lf\n",i,!A[i][n+1]/A[i][i]?0:A[i][n+1]/A[i][i]);
    return 0;
}

求改正

绝望的蒟