June 2018 Update

Task/Priority-queue/C/priority-queue.c

@@ -35,11 +35,14 @@ char *pop (heap_t *h) {
         return NULL;
     }
     char *data = h->nodes[1].data;
+
     h->nodes[1] = h->nodes[h->len];
+
     h->len--;
+
     i = 1;
-    while (1) {
-        k = i;
+    while (i!=h->len+1) {
+        k = h->len+1;
         j = 2 * i;
         if (j <= h->len && h->nodes[j].priority < h->nodes[k].priority) {
             k = j;
@@ -47,13 +50,9 @@ char *pop (heap_t *h) {
         if (j + 1 <= h->len && h->nodes[j + 1].priority < h->nodes[k].priority) {
             k = j + 1;
         }
-        if (k == i) {
-            break;
-        }
         h->nodes[i] = h->nodes[k];
         i = k;
     }
-    h->nodes[i] = h->nodes[h->len + 1];
     return data;
 }
 

Task/Priority-queue/Nim/priority-queue-2.nim

@@ -1,18 +1,12 @@
-import tables
+import HeapQueue
 
-var
-  pq = initTable[int, string]()
+var pq = newHeapQueue[(int, string)]()
 
-proc main() =
-  pq.add(3, "Clear drains")
-  pq.add(4, "Feed cat")
-  pq.add(5, "Make tea")
-  pq.add(1, "Solve RC tasks")
-  pq.add(2, "Tax return")
+pq.push((3, "Clear drains"))
+pq.push((4, "Feed cat"))
+pq.push((5, "Make tea"))
+pq.push((1, "Solve RC tasks"))
+pq.push((2, "Tax return"))
 
-  for i in countUp(1,5):
-    if pq.hasKey(i):
-      echo i, ": ", pq[i]
-      pq.del(i)
-
-main()
+while pq.len() > 0:
+    echo pq.pop()

Task/Priority-queue/Nim/priority-queue-3.nim

@@ -0,0 +1,18 @@
+import tables
+
+var
+  pq = initTable[int, string]()
+
+proc main() =
+  pq.add(3, "Clear drains")
+  pq.add(4, "Feed cat")
+  pq.add(5, "Make tea")
+  pq.add(1, "Solve RC tasks")
+  pq.add(2, "Tax return")
+
+  for i in countUp(1,5):
+    if pq.hasKey(i):
+      echo i, ": ", pq[i]
+      pq.del(i)
+
+main()

Task/Priority-queue/REXX/priority-queue-1.rexx

@@ -1,5 +1,5 @@
-/*REXX program implements a priority queue;  with  insert/display/delete  the top task. */
-#=0;  @.=                                        /*0 tasks;  nullify the priority queue.*/
+/*REXX program implements a  priority queue   with  insert/display/delete  the top task.*/
+#=0;   @.=                                       /*0 tasks;  nullify the priority queue.*/
 say '══════ inserting tasks.';     call .ins  3  "Clear drains"
                                    call .ins  4  "Feed cat"
                                    call .ins  5  "Make tea"
@@ -11,16 +11,12 @@ say '══════ showing tasks.';       call .show
 say '══════ deletes top task.';    say .del()    /*delete the top task.                 */
 exit                                             /*stick a fork in it,  we're all done. */
 /*──────────────────────────────────────────────────────────────────────────────────────*/
-.del:  procedure expose @. #; parse arg p; if p==''  then p=.top(); x=@.p; @.p=;  return x
-    /*delete the top task entry.           */
-/*──────────────────────────────────────────────────────────────────────────────────────*/
+.del:  procedure expose @. #; arg p;  if p=''  then p=.top();    y=@.p;   @.p=;   return y
 .ins:  procedure expose @. #; #=#+1;  @.#=arg(1);    return #          /*entry, P, task.*/
-/*──────────────────────────────────────────────────────────────────────────────────────*/
-.show: procedure expose @. #; do j=1  for #;  _=@.j;  if _==''  then iterate;  say _;  end
-       return                                      /* [↑]  show whole list or just one. */
+.show: procedure expose @. #; do j=1  for #;  _=@.j;  if _\==''  then say _;  end;  return
 /*──────────────────────────────────────────────────────────────────────────────────────*/
 .top:  procedure expose @. #;      top=;              top#=
-                   do j=1  for #;  _=word(@.j,1);     if _==''  then iterate
-                   if top=='' | _>top  then do;   top=_;   top#=j;   end
+                   do j=1  for #;  _=word(@.j, 1);    if _==''  then iterate
+                   if top=='' | _>top  then do;    top=_;    top#=j;    end
                    end   /*j*/
        return top#

Task/Priority-queue/XLISP/priority-queue-1.xlisp

@@ -0,0 +1,35 @@
+(define-class priority-queue
+	(instance-variables queue lowest-priority most-urgent) )
+
+(define-method (priority-queue 'initialize limit)
+	(defun setup (x)
+		(vector-set! queue x nil)
+		(if (< x limit)
+			(setup (+ x 1)) ) )
+	(setq lowest-priority limit)
+	(setq most-urgent limit)
+	(setq queue (make-vector (+ limit 1)))
+	(setup 0)
+	self )
+
+(define-method (priority-queue 'push item priority)
+	(if (and (integerp priority) (>= priority 0) (<= priority lowest-priority))
+		(progn
+			(setq most-urgent (min priority most-urgent))
+			(vector-set! queue priority (nconc (vector-ref queue priority) (cons item nil))) ) ) )
+
+(define-method (priority-queue 'pop)
+	(defun find-next (q)
+		(if (or (= q lowest-priority) (not (null (vector-ref queue q))))
+			q
+			(find-next (+ q 1)) ) )
+	(define item (car (vector-ref queue most-urgent)))
+	(vector-set! queue most-urgent (cdr (vector-ref queue most-urgent)))
+	(setq most-urgent (find-next most-urgent))
+	item )
+
+(define-method (priority-queue 'peek)
+	(car (vector-ref queue most-urgent)) )
+
+(define-method (priority-queue 'emptyp)
+	(and (= most-urgent lowest-priority) (null (vector-ref queue most-urgent))) )

Task/Priority-queue/XLISP/priority-queue-10.xlisp

@@ -0,0 +1,3 @@
+[13] (pq 'pop)
+
+()

Task/Priority-queue/XLISP/priority-queue-2.xlisp

@@ -0,0 +1,7 @@
+(define pq (priority-queue 'new 5))
+
+(pq 'push "Clear drains" 3)
+(pq 'push "Feed cat" 4)
+(pq 'push "Make tea" 5)
+(pq 'push "Solve RC tasks" 1)
+(pq 'push "Tax return" 2)

Task/Priority-queue/XLISP/priority-queue-3.xlisp

@@ -0,0 +1,6 @@
+[1] (pq 'pop)
+
+"Solve RC tasks"
+[2] (pq 'pop)
+
+"Tax return"

Task/Priority-queue/XLISP/priority-queue-4.xlisp

@@ -0,0 +1,3 @@
+[3] (pq 'push "Answer emails" 4)
+
+("Feed cat" "Answer emails")

Task/Priority-queue/XLISP/priority-queue-5.xlisp

@@ -0,0 +1,3 @@
+[4] (pq 'push "Weed garden" 17)
+
+()

Task/Priority-queue/XLISP/priority-queue-6.xlisp

@@ -0,0 +1,3 @@
+[5] (pq 'emptyp)
+
+()

Task/Priority-queue/XLISP/priority-queue-7.xlisp

@@ -0,0 +1,3 @@
+[6] (pq 'peek)
+
+"Clear drains"

Task/Priority-queue/XLISP/priority-queue-8.xlisp

@@ -0,0 +1,8 @@
+[7] (pq 'show)
+
+Object is #<Object:PRIORITY-QUEUE #x4e2cba8>, Class is #<Class:PRIORITY-QUEUE #x4e254c8>
+Instance variables:
+  QUEUE = #(() () () ("Clear drains") ("Feed cat" "Answer emails") ("Make tea"))
+  LOWEST-PRIORITY = 5
+  MOST-URGENT = 3
+#<Object:PRIORITY-QUEUE #x4e2cba8>

Task/Priority-queue/XLISP/priority-queue-9.xlisp

@@ -0,0 +1,15 @@
+[8] (pq 'pop)
+
+"Clear drains"
+[9] (pq 'pop)
+
+"Feed cat"
+[10] (pq 'pop)
+
+"Answer emails"
+[11] (pq 'pop)
+
+"Make tea"
+[12] (pq 'emptyp)
+
+#T