#include <stdio.h>
#include <stdlib.h>
#include <time.h>

void genera(int **map,int size);
int main()
{
  srand(time(NULL));
  int size=rand() % 20 + 3;
  int **map,i;

  map = calloc(size,sizeof(int*));
  for(i=0;i<size;i++)
  {
    map[i]=calloc(size,sizeof(int));
  }
  genera(map,size);

  /*
  for(int i=0;i<size;i++)
  {
    for(int j=0;j<size;j++)
    {
      printf("%d",*(*map+i*size+j));
    }
  }
  */
}

void genera(int **map,int size)
{
  int righe=size;
  int colonne=size;
  int pos=0;
  int count=0;
  int continua;
  int pos_cur[20]={0};
  int rand_continua=0;

  int x_pos_uscita= rand() %size + 1;
  int y_pos_uscita= rand() %size + 1;

//this creates a matrix made of 0s and 1s.
  for(int i=0;i<righe;i++)
  {
    for(int j=0;j<colonne;j++)
    {
      *(*map+i*colonne+j)= rand() % 2;
    }
  }


  for(int i=1;i<righe;i++)
  {
    for(int j=0;j<colonne;j++)
    {
      if (*(*map+(i-1)*colonne+j)==0)
      {
        /*in this for loop, im checking if theres a 0 in the previous row of the
        previous row of the matrix, if yes, save the position of the current column
        inside a array called pos_cur, and keep a counter of the number of 0s found
        inside a variable count.
        example:
        00114
        23450
        this stores the positions 0 and 1 inside pos_cur and sets count to 2*/

        pos_cur[pos]=j;
        pos++;
        count++;
      }
    }

    //this variable creates a random number between 0 and the number of 0s found previously
    continua=rand() %count;

    for(int k=0;k<continua;k++)
    {
      /*this for loop creates a random number between 0s and the number of 0s found,
      if it hasnt been used yet, it uses the position stored inside the array pos_cur
      to change the number of the original matrix to 0;
      example:
      00104
      23450  ->count=3, pos_cur={0,1,3}
      continua=random number between 0 and 2, lets say 1;
      for a "continua" number of times(1), finds a random number betwen 0 and 2 that
      has not been used yet, lets say 2;
      as pos_cur[2]=3, the column 3 (+1 because it starts from 0) at line i in the original matrix is changed to 0:
      00104
      234(0)0
      */
      rand_continua=rand() %count;
      if(pos_cur[rand_continua]!=-1)
      {
        *(*map+i*colonne+pos_cur[rand_continua])= 0;
        pos_cur[rand_continua]=-1;
      }
      else
      {
        k--;
      }
    }
    count=0;
  }

}