Cod sursa(job #903498)

Utilizator nosurrender99Bura Bogdan nosurrender99 Data 1 martie 2013 21:26:39
Problema Algoritmul lui Gauss Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 1.6 kb
#include <fstream>
#include <iomanip>
#include <cstdlib>
using namespace std;
#define EPS 0.0000001

fstream f("gauss.in", ios::in), g("gauss.out", ios::out);

double a[303][303],X[303];
int m,n;
void solve();

int main()
{
    f>>n>>m;
    for(int i=1;i<=n;i++)
        for(int j=1;j<=m+1;j++)
            f>>a[i][j];
    solve();
    for(int i=1;i<=m;i++)
    {
        g<<fixed<<setprecision (8)<<X[i]<<" ";
    }
    return 0;
}

void solve()
{
    for(int i=1,j=1;i<=n && j<=m;j++,i++)
    {
        int P = -1;
        for(int k = i; k <= n; ++k)
            if(a[k][j] >EPS || a[k][j] < -EPS){
                P = k; break;
            }

        if(P == -1)
        {
            g << "Imposibil";
            exit(0);
        }
        if(P != n)
            for(int k = 1; k <= m + 1; ++k)
                swap(a[P][k], a[i][k]);

            double D = a[i][j];
        for(int k = 1; k <= m + 1; ++k)
            a[i][k] = a[i][k] / D;

        for(int l = i + 1; l <= n; ++l)
        {
            D = -a[l][j];
            for(int k = j; k <= m + 1; ++k)
                a[l][k] = a[l][k] + D * a[i][k];
        }
        }
      for(int i = n; i>0; --i)
        for(int j = 1; j <= m+1; ++j)
            if(a[i][j]>EPS || a[i][j]<-EPS)
            {
                if(j == m+1)
                {
                    g<<"Imposibil"<<endl;
                    exit(0);
                }
                X[j] = a[i][m+1];
                for(int k = j+1; k <= m; ++k)
                    X[j] -= X[k] * a[i][k];

                break;
            }
}