http://snippets.dzone.com/posts Fri, 08 Aug 2008 13:28:08 GMT DZone Snippets: subset code http://snippets.dzone.com/posts/show/4631 This code generates all the subsets of {1, 2, ..., n} and prints them. <br /> <br />This also contains a very fast binary counter implementation. <br /> <br />See <a href="http://compprog.wordpress.com/2007/10/10/generating-subsets/">this</a> for further explanations. <br /> <br /><code> <br />#include <stdio.h> <br /> <br />/* Applies the mask to a set like {1, 2, ..., n} and prints it */ <br />void printv(int mask[], int n) { <br /> int i; <br /> printf("{ "); <br /> for (i = 0; i < n; ++i) <br /> if (mask[i]) <br /> printf("%d ", i + 1); /*i+1 is part of the subset*/ <br /> printf("\b }\n"); <br />} <br /> <br />/* Generates the next mask*/ <br />int next(int mask[], int n) { <br /> int i; <br /> for (i = 0; (i < n) && mask[i]; ++i) <br /> mask[i] = 0; <br /> <br /> if (i < n) { <br /> mask[i] = 1; <br /> return 1; <br /> } <br /> return 0; <br />} <br /> <br />int main(int argc, char *argv[]) { <br /> int n = 3; <br /> <br /> int mask[16]; /* Guess what this is */ <br /> int i; <br /> for (i = 0; i < n; ++i) <br /> mask[i] = 0; <br /> <br /> /* Print the first set */ <br /> printv(mask, n); <br /> <br /> /* Print all the others */ <br /> while (next(mask, n)) <br /> printv(mask, n); <br /> <br /> return 0; <br />} <br /></code> Wed, 10 Oct 2007 14:43:25 GMT http://snippets.dzone.com/posts/show/4631 scvalex (Alexandru Scvortov) http://snippets.dzone.com/posts/show/1123 <code> <br /> subset?: func [ <br /> {Returns true if A is a subset of B; false otherwise.} <br /> a [series! bitset!] <br /> b [series! bitset!] <br /> ] [ <br /> empty? exclude a b <br /> ] <br /> <br /> superset?: func [ <br /> {Returns true if set1 is a superset of set2; false otherwise.} <br /> set1 [series! bitset!] <br /> set2 [series! bitset!] <br /> ][ <br /> subset? set2 set1 <br /> ] <br /></code> Tue, 10 Jan 2006 06:15:05 GMT http://snippets.dzone.com/posts/show/1123 gregg.irwin (Gregg Irwin)