Problemes sur exo de programmation

#include <stdio.h>
#define LONGUEUR 20

int main (void)
{
  int i, j, k, t;
  for (i = 0; i < LONGUEUR; ++i){
    for (j = 0; j < (LONGUEUR - i) - 1; ++j)
      printf (" ");
    printf ("*");
    if (i > 0){
      for (k = 0; k < 2 * i - 1; ++k)
        printf (" ");
      printf ("*");
    }
    printf ("\n");
  }
  t = k - 2;
  for (i = 1; i < LONGUEUR; ++i){
    for (j = 0; j < i; ++j)
      printf (" ");
    printf ("*");
    if (i < LONGUEUR - 1){
      for (k = 0; k < t; ++k)
        printf (" ");
      printf ("*");
      t = t - 2;
    }
    printf ("\n");
  }
  return 0;
}

lami20j@debian:~/trash$ ./a.out
                   *
                  * *
                 *   *
                *     *
               *       *
              *         *
             *           *
            *             *
           *               *
          *                 *
         *                   *
        *                     *
       *                       *
      *                         *
     *                           *
    *                             *
   *                               *
  *                                 *
 *                                   *
*                                     *
 *                                   *
  *                                 *
   *                               *
    *                             *
     *                           *
      *                         *
       *                       *
        *                     *
         *                   *
          *                 *
           *               *
            *             *
             *           *
              *         *
               *       *
                *     *
                 *   *
                  * *
                   *
lami20j@debian:~/trash$