Heap datastructure added

data-structures/heap.rb

@@ -0,0 +1,64 @@
+class Heap
+    attr_accessor :heap_size, :array_rep
+    def left_child(index)
+      2*index + 1
+    end
+  
+    def right_child(index)
+      2*index + 2
+    end
+  
+    def left_child_key(index)
+      @array_rep[left_child(index)]
+    end
+  
+    def right_child_key(index)
+      @array_rep[right_child(index)]
+    end
+
+    def leaf_node?(index)
+        return index >= @heap_size/2
+    end
+
+    def satisfied?(index)
+        @array_rep[index] >= left_child_key(index) and 
+          @array_rep[index] >= right_child_key(index)
+    end
+
+    def heapify(index)
+        return if leaf_node?(index) || satisfied?(index)
+    
+        left_child_key = @array_rep[left_child(index)]
+        right_child_key = @array_rep[right_child(index)]
+    
+        larger_child = if left_child_key > right_child_key then left_child(index)
+          else right_child(index) end
+    
+        @array_rep[index], @array_rep[larger_child] = @array_rep[larger_child], 
+          @array_rep[index]
+    
+        heapify(larger_child)
+    end
+
+    def create_max_heap
+        (0..@heap_size/2-1).to_a.reverse.each do |index|  
+          heapify(index)
+        end
+    end
+
+    def get_max
+        array_rep[0]
+    end
+
+    def remove_max
+        array_rep[@heap_size-1], array_rep[0] = array_rep[0], array_rep[@heap_size-1]
+        @heap_size -= 1
+        heapify(0)
+    end
+
+end
+
+heap = Heap. new
+heap.heap_size = 15
+heap.array_rep = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
+heap.create_max_heap