10.8 Lab: Heap - Display Heap as an Indented List

Change the previous lab to display a min-heap as an indented list (level numbers included). In order to do this you will have to add two new member functions to the heap class

- void _printIndented(int index, void visit(int, int)); // A
- void printIndented(void visit(int, int)); // B

Note: One function would be sufficient(A). However, to make the call simpler, a wrapper function (B) has been added (to "hide" the root of the heap).

Another solution is to add level as a parameter to _printIndented:

- void _printIndented(int index, int level, void visit(int, int));

07-heaps/Heap.cpp

@@ -83,3 +83,12 @@ bool Heap::deleteHeap(int &returnItem) {
 
     return true;
 }
+
+void Heap::_printIndented(int index, int level, void (*visit)(int item, int level)) {
+    if (_findRightChild(index) != -1)
+        _printIndented(_findRightChild(index), level + 1, visit);
+    visit(heapAry[index], level);
+    if (_findLeftChild(index) != -1)
+        _printIndented(_findLeftChild(index), level + 1, visit);
+
+}

07-heaps/Heap.h

@@ -49,6 +49,11 @@ public:
     bool insertHeap(int itemIn);
 
     bool deleteHeap(int &itemOut);
+
+    // other functions added
+    void printIndented(void visit(int item, int level)) { _printIndented(0, 0, visit); };
+
+    void _printIndented(int index, int level, void visit(int item, int level));
 };
 
 #endif

07-heaps/main.cpp

@@ -1,7 +1,8 @@
 /*
-  This program will read integers from the keyboard,
-  insert them into a min-heap, and display them as
-  they are deleted from the heap.
+  This program will
+     - read integers from the keyboard and insert them into a min-heap,
+     - display the min-heap as an indented list (level numbers included) and
+     - display the integers as they are deleted from the heap.
 */
 
 #include <iostream>
@@ -9,11 +10,11 @@
 
 using namespace std;
 
+void iDisplay(int item, int level);
+
 int main() {
-
     Heap heap;
 
-
     // build heap
     int num;
     cout << "Enter integers [0 - to stop]" << endl;
@@ -22,14 +23,14 @@ int main() {
         heap.insertHeap(num);
         cin >> num;
     }
-
     cout << "Heap capacity: " << heap.getSize() << endl;
     cout << "Heap actual number of elements: " << heap.getCount() << endl;
 
+    heap.printIndented(iDisplay);
+
     // print items as they are deleted from the heap (sorted)
-    if (heap.isEmpty()) {
+    if (heap.isEmpty())
         cout << "N/A";
-    }
     while (!heap.isEmpty()) {
         heap.deleteHeap(num);
         cout << num << " ";
@@ -38,3 +39,15 @@ int main() {
 
     return 0;
 }
+
+
+/*
+  indented display:
+  displays one item including the level number
+  and corresponding indentation
+*/
+void iDisplay(int item, int level) {
+    for (int i = 0; i < level; i++)
+        cout << "..";
+    cout << level << "). " << item << endl;
+}