#include <stdio.h>
#include <conio.h>

void printMatrix(float** B, int n)//print the matrix
{
  printf("\n");
  int x ,y;
  for(y=0; y<n; y++)
     {
   for(x=0; x<n; ++x)
   printf("%7.2f", B[x][y]);
   printf("\n");
     }
     printf("\n");
}
void swap_columns(float** B, int col1, int col2)
{
  float* temp = B[col1];
  B[col1] = B[col2];
  B[col2] = temp;
}
void swap_rows(float** B, int row1, int row2, int n)
{
     float temp;
     for(int i=0; i<n; ++i)
   {
   temp = B[i][row1];
   B[i][row1] = B[i][row2];
   B[i][row2] = temp;
   }
}
         
int main()
{
       int n=3,x,y;
       float **matr=new float*[n];
       for(x=0;x<n;++x)
       matr[x]=new float[n];
       for(y=0;y<n;++y)
       for(x=0;x<n;++x)
       scanf("%f",&matr[x][y]);
       printMatrix(matr, n);  
       float determ=1.0;
       int sign = +1;
       for(int i=0; i<n; ++i) //move along main diagonal
       {
     int nonull_x = 0, nonull_y = 0;
     bool success_finding_nonull_element = false;
     for(x = i; x<n; ++x)
     for(y = i; y<n; ++y)
     if(!success_finding_nonull_element && matr[x][y])
     {
      nonull_x = x;
      nonull_y = y;
      success_finding_nonull_element = true;
     }
     if(!success_finding_nonull_element) //no non-null elements
     {
      determ = 0.0;
      break;
     }
     if(nonull_x != i)
     {
      swap_columns(matr, i, nonull_x);
      sign = -sign;
     }
     if(nonull_y != i)
     {
     swap_rows(matr, i, nonull_y, n);
     sign = -sign;
     }
     determ *= matr[i][i];
     for(x=n-1; x>=i; --x)
     matr[x][i] /= matr[i][i];
     for (y=i+1; y<n; ++y)
     for (x=n-1; x>=i; --x)
     matr[x][y] -= matr[x][i]*matr[i][y];
       }
       determ *= sign;
       printf("determinant = %f\n", determ);
       getch();
       for(x=0; x<n; ++x)
       delete[] matr[x];
       delete[] matr;
       return 0;
}