A solution for Project Three

/* MCS 275 Project Three: Knapsack */

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

void knapsack ( int n );
/* prints out subsets of n elements on screen */
void all_sets ( int n, int k, int a[n], int w[n],
                int max, int freq[max], int *cnt );
/* recursive version of all subsets */

int main()
{
   int n;

   printf("Solving the knapsack problem.\n");
   printf("Give number of items : "); scanf("%d", &n);
   knapsack(n);

   return 0;
}

void knapsack ( int n )
{
   int i,a[n],w[n],max,cnt=0;
   int *freq;
 
   for (i = 0; i < n; i++)
   {
      a[i] = 0;
      printf("Give weight of item %d : ", i+1);
      scanf("%d", &w[i]);
   }
   printf("Give maximal admitted weight : ");
   scanf("%d",&max);
   printf("All ways to pack %d items, with total weight <= %d :\n", n, max);
   freq = (int*)calloc(max+1,sizeof(int));
   all_sets(n,0,a,w,max,freq,&cnt);
   printf("Admitted solutions : %d, all with total weight <= %d :\n", cnt, max);
   for (i = 0; i <= max; i++)
     printf("  number of solutions with total weight = %d : %d\n", i, freq[i]);
}

void all_sets ( int n, int k, int a[n], int w[n], int max,
                int freq[max], int *cnt )
{
   int i,sum = 0;

   if (k == n)
   {
      for (i = 0; i < n; i++)
      {
         printf(" %d", a[i]);
         if (a[i]==1) sum = sum + w[i];
      }
      printf(" total weight : %d", sum);
      if (sum <= max)
      {
         printf(" admitted, less than or equal to %d.\n", max);
         *cnt = *cnt+1;
         freq[sum]++;
      }
      else
         printf(" is heavier than %d, not admitted!\n", max);
   }
   else
   {
      all_sets(n,k+1,a,w,max,freq,cnt);
      a[k] = 1;
      all_sets(n,k+1,a,w,max,freq,cnt);
      a[k] = 0;
   }
}