all tasks

Task/Sorting-algorithms-Heapsort/Seed7/sorting-algorithms-heapsort.seed7

@@ -0,0 +1,39 @@
+const proc: downheap (inout array elemType: arr, in var integer: k, in integer: n) is func
+  local
+    var elemType: help is elemType.value;
+    var integer: j is 0;
+  begin
+    if k <= n div 2 then
+      help := arr[k];
+      repeat
+        j := 2 * k;
+        if j < n and arr[j] < arr[succ(j)] then
+          incr(j);
+        end if;
+        if help < arr[j] then
+          arr[k] := arr[j];
+          k := j;
+        end if;
+      until help >= arr[j] or k > n div 2;
+      arr[k] := help;
+    end if;
+  end func;
+
+const proc: heapSort (inout array elemType: arr) is func
+  local
+    var integer: n is 0;
+    var integer: k is 0;
+    var elemType: help is elemType.value;
+  begin
+    n := length(arr);
+    for k range n div 2 downto 1 do
+      downheap(arr, k, n);
+    end for;
+    repeat
+      help := arr[1];
+      arr[1] := arr[n];
+      arr[n] := help;
+      decr(n);
+      downheap(arr, 1, n);
+    until n <= 1;
+  end func;