1 files changed, 79 insertions, 0 deletions
diff --git a/reference/C/CONTRIB/SNIP/permute2.c b/reference/C/CONTRIB/SNIP/permute2.c
new file mode 100755
index 0000000..2cad78a
--- /dev/null
+++ b/reference/C/CONTRIB/SNIP/permute2.c
@@ -0,0 +1,79 @@
+/*
+**  PERMUTE.C - prints all permutations of an input string
+**
+**  public domain demo by Jon Guthrie
+*/
+
+#include    <string.h>
+#include    <stdlib.h>
+#include    <stdio.h>
+
+int     charcmp(char *, char *);
+
+void    permute(char *, int, int);
+
+int     main(int argc, char *argv[])
+{
+      int length;
+
+      if (2 > argc)
+      {
+            puts("Usage: PERMUTE string");
+            abort();
+      }
+      
+      length = strlen(argv[1]);
+
+      /* It only works if they're printed in order */
+
+      qsort(argv[1], length, 1, (int(*)(const void *, const void *))charcmp);
+
+      permute(argv[1], 0, length);
+      return 0;
+}
+
+
+/*
+**  This function prints all of the permutations of string "array"
+**  (which has length "len") starting at "start."
+*/
+
+void    permute(char *array, int start, int len)
+{
+      int j;
+      char    *s;
+
+      if(start < len)
+      {
+            if(NULL == (s = malloc(len)))
+            {
+                  printf("\n\nMemory error!!!\a\a\n");
+                  abort();
+            }
+
+            strcpy(s, array);
+            for(j=start ; j<len ; ++j)
+            {
+                  int     temp;
+
+                  if((j == start) || (s[j] != s[start]))
+                  {     /* For each character that's different    */
+                        /* Swap the next first character with...  */
+                        /* the current first                      */
+                        temp = s[j];
+                        s[j] = s[start];
+                        s[start] = temp;
+                        permute(s, start+1, len);
+                  }
+            }
+            free(s);
+      }
+      else	puts(array);
+}
+
+
+
+int charcmp(char *a, char *b)
+{
+      return(*a - *b);
+}