September 2017 Update

Task/Sorting-algorithms-Quicksort/ALGOL-W/sorting-algorithms-quicksort-1.alg

@@ -0,0 +1,26 @@
+% Quicksorts in-place the array of integers v, from lb to ub %
+procedure quicksort ( integer array v( * )
+                    ; integer value lb, ub
+                    ) ;
+if ub > lb then begin
+    % more than one element, so must sort %
+    integer left, right, pivot;
+    left   := lb;
+    right  := ub;
+    % choosing the middle element of the array as the pivot %
+    pivot  := v( left + ( ( right + 1 ) - left ) div 2 );
+    while begin
+        while left  <= ub and v( left  ) < pivot do left  := left  + 1;
+        while right >= lb and v( right ) > pivot do right := right - 1;
+        left <= right
+    end do begin
+        integer swap;
+        swap       := v( left  );
+        v( left  ) := v( right );
+        v( right ) := swap;
+        left       := left  + 1;
+        right      := right - 1
+    end while_left_le_right ;
+    quicksort( v, lb,   right );
+    quicksort( v, left, ub    )
+end quicksort ;

Task/Sorting-algorithms-Quicksort/ALGOL-W/sorting-algorithms-quicksort-2.alg

@@ -0,0 +1,3 @@
+      qsort ← {1≥⍴⍵:⍵ ⋄ e←⍵[?⍴⍵] ⋄ (∇(⍵<e)/⍵) , ((⍵=e)/⍵) , (∇(⍵>e)/⍵)}
+      qsort 31 4 1 5 9 2 6 5 3 5 8
+1 2 3 4 5 5 5 6 8 9 31