Init

quicksort.c

@@ -0,0 +1,70 @@
+# include <stdio.h>
+
+# define PRINT(X) \
+	       {int i;						\
+                printf ("%-10s", X);				\
+		for (i = 0; i < 4; i++) printf (" %2d ", a[i]);	\
+		printf ("\n");					\
+               }
+
+void quicksort (int *a, int links, int rechts)
+/* sortiert die Elemente a[links] .. a[rechts] */
+{
+  /* partitioniere a[links] .. a[rechts] */
+  int m = (links + rechts) / 2 ;
+  int x = a[m];
+  int l = links, r = rechts;
+
+  PRINT ("\nvor part");
+  printf ("l=%d m=%d x=%d, r=%d\n", l, m, x, r);
+  while (l <= r) {
+    while (a[l] < x) l++;
+    printf ("von links: l=%d\n", l);
+    while (a[r] > x) r--;
+    printf ("von rechts: r=%d\n", r);
+
+    if (l <= r) {
+      int t = a[l]; a[l] = a[r]; a[r] = t;
+                                    /* a[l] <-> a[r] */
+      l++; r--;   /* "verschiebe Pfeile" */
+      PRINT ("nach swap");
+    }
+  }
+
+  printf ("l=%d m=%d x=%d, r=%d\n", l, m, x, r);
+  PRINT ("nach part");
+
+  /* Sortiere linken und rechten Teilarray */
+  if (links < r)      quicksort (a, links, r);
+  if (l     < rechts) quicksort (a, l,     rechts);
+}
+
+
+int main (int argc, char *argv[])
+{
+  int a[5] = {58,91,28,80,54};
+
+  PRINT ("start");
+  /*
+  int l = 0, r = 1;
+  int m = 2;
+  int x = a[m];
+  int i;
+
+  while (l <= r) {
+    while (a[l] < x) l++;
+    printf ("von links: l=%d\n", l);
+    while (a[r] > x) r--;
+    printf ("von rechts: l=%d\n", l);
+    if (l <= r) {
+      int t = a[l]; a[l] = a[r]; a[r] = t;
+      l++; r--;
+    }
+  }
+  */
+
+  quicksort (a, 0, 4);
+
+  PRINT ("res");
+  return 0;
+}