高斯消元

很高深

 

#include<cstdio>
#include<cstring>
int n,i,j,k;
double a[502][502];
double x[502],t;
int main()
{
    freopen("shopping.in","r",stdin);
    freopen("shopping.out","w",stdout);
    scanf("%d\n",&n);
    for (i=1;i<=n;i++)
    for (j=1;j<=n+1;j++)
    {
         int x;
      scanf("%d",&x);
      a[i][j]=x;
    }
    for (i=1;i<=n-1;i++)
    for (j=i+1;j<=n;j++)
    {
        t=a[j][i]/a[i][i];
        a[j][i]=0;
        for (k=i+1;k<=n+1;k++)
          a[j][k]=a[j][k]-(t*a[i][k]);
    }
    x[n]=(a[n][n+1]/a[n][n]);
    for (i=n-1;i>0;i--)
    {
        t=a[i][n+1];
        for (j=n;j>=i+1;j--)
        t-=x[j]*a[i][j];
        x[i]=t/a[i][i];
    }
    for (i=1;i<=n;i++) printf("%.f\n",x[i]);
    return 0;
}