September 2017 Update

Task/Sorting-algorithms-Quicksort/Zkl/sorting-algorithms-quicksort-1.zkl

@@ -0,0 +1,8 @@
+fcn qtSort(list,cmp=Op("<")){	// sort immutable lists
+   fcn(list,cmp,N){	// spendy to keep recreating cmp
+      reg pivot=list[0], rest=list[1,*];
+      left,right:=rest.filter22(cmp,pivot);
+      N+=1;
+      T.extend(self.fcn(left,cmp,N),T(pivot),self.fcn(right,cmp,N));
+   }(list,cmp,0);
+}

Task/Sorting-algorithms-Quicksort/Zkl/sorting-algorithms-quicksort-2.zkl

@@ -0,0 +1,24 @@
+fcn qiSort(list,cmp='<){		// in place quick sort
+   fcn(list,left,right,cmp){
+      if (left<right){
+	 // partition list
+	 pivotIndex:=(left+right)/2; // or median of first,middle,last
+	 pivot:=list[pivotIndex];
+	 list.swap(pivotIndex,right);	// move pivot to end
+	 pivotIndex:=left;
+	 i:=left; do(right-left){	// foreach i in ([left..right-1])
+	    if(cmp(list[i],pivot)){	// not cheap
+	       list.swap(i,pivotIndex);
+	       pivotIndex+=1;
+	    }
+	    i+=1;
+	 }
+	 list.swap(pivotIndex,right);	// move pivot to final place
+
+	 // sort the partitions
+         self.fcn(list,left,pivotIndex-1,cmp);
+	 return(self.fcn(list,pivotIndex+1,right,cmp));
+      }
+   }(list,0,list.len()-1,cmp);
+   list;
+}