Triangle de Pascal (INFO2009-Repetition 4)

trianglepascal.c

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

int **triangle_pascal(int n);

int main(int argc, const char **argv){
  int n = (argc > 1) ? atoi(argv[1]) : 10;
  int **triangle = triangle_pascal(n);
  int x, y;
  
  if (! triangle)
    return 1;
  
  for (y=0; y<n; y++){
    for (x=0; x<n; x++)
      printf("%8d", triangle[x][y]);
    printf("\n");
  }
  
  for (x=0; x<n; x++)
    free(triangle[x]);
  free(triangle);
  return 0;
}

int **triangle_pascal(int n){
  int **res = NULL;
  int x, y;
  
  if (n < 1)
    return NULL;
  
  //si erreur d'allocation, on renvoie NULL
  res = malloc(n*sizeof(int *));
  if (! res)
    return NULL;
    
  for (x=0; x<n; x++){
    res[x] = malloc(n*sizeof(int));
    
    //si erreur d'allocation, on libere tout ce qui a ete alloue jusque la 
    //et on renvoie NULL
    if (! res[x]){
      for (y=0; y<x; y++)
        free(res[y]);
      free(res);
      return NULL;
    }
  }
  
  res[0][0] = 1;
  for (x=1; x<n; x++){
    res[x][0] = 1;
    res[0][x] = 1;
  }
  for (x=1; x<n; x++)
    for (y=1; y<n; y++)
      res[x][y] = res[x-1][y] + res[x][y-1];
      
  return res;
}