From ac907d8a6f032d990a9c2be4140d226db9a2db69 Mon Sep 17 00:00:00 2001
From: Nidhi <nidhixpatel@gmail.com>
Date: Thu, 19 Sep 2019 15:44:55 -0700
Subject: [PATCH 1/5] working on min heap

---
 lib/min_heap.rb | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/lib/min_heap.rb b/lib/min_heap.rb
index 6eaa630..158b73d 100644
--- a/lib/min_heap.rb
+++ b/lib/min_heap.rb
@@ -1,6 +1,6 @@
 class HeapNode
   attr_reader :key, :value
-
+  # compare by key, priority field
   def initialize(key, value)
     @key = key
     @value = value
@@ -17,7 +17,13 @@ def initialize
   # Time Complexity: ?
   # Space Complexity: ?
   def add(key, value = key)
-    raise NotImplementedError, "Method not implemented yet..."
+    new_node = HeapNode.new(key, value)
+    new_node_index = @store.length
+    @store.push(new_node)
+    if new_node_index > 2
+     parent_node = find_parent()
+    end
+    return new_node
   end
 
   # This method removes and returns an element from the heap
@@ -52,6 +58,14 @@ def empty?
 
   private
 
+  def find_parent(index)
+    parent_index = (index - 1)/2
+    return parent_index
+  end
+
+
+
+
   # This helper method takes an index and
   #  moves it up the heap, if it is less than it's parent node.
   #  It could be **very** helpful for the add method.

From f771d0b645a1f3012cba935fadc6aeadae7cb4eb Mon Sep 17 00:00:00 2001
From: Nidhi <nidhixpatel@gmail.com>
Date: Thu, 19 Sep 2019 15:59:14 -0700
Subject: [PATCH 2/5] working on heap up

---
 lib/min_heap.rb | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/lib/min_heap.rb b/lib/min_heap.rb
index 158b73d..a9afb3f 100644
--- a/lib/min_heap.rb
+++ b/lib/min_heap.rb
@@ -20,8 +20,8 @@ def add(key, value = key)
     new_node = HeapNode.new(key, value)
     new_node_index = @store.length
     @store.push(new_node)
-    if new_node_index > 2
-     parent_node = find_parent()
+    if @store.length > 1
+      heap_up(@store.length - 1)
     end
     return new_node
   end
@@ -63,15 +63,16 @@ def find_parent(index)
     return parent_index
   end
 
-
-
-
   # This helper method takes an index and
   #  moves it up the heap, if it is less than it's parent node.
   #  It could be **very** helpful for the add method.
   # Time complexity: ?
   # Space complexity: ?
   def heap_up(index)
+    p = find_parent(index)
+    if @store[p].key < @store[index].key
+      swap(p, index)
+    end
     
   end
 

From f134a04535e2a185fc71ffa2f12ddf22f13a089b Mon Sep 17 00:00:00 2001
From: Nidhi <nidhixpatel@gmail.com>
Date: Thu, 19 Sep 2019 16:11:06 -0700
Subject: [PATCH 3/5] recursive heap up

---
 lib/min_heap.rb | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/lib/min_heap.rb b/lib/min_heap.rb
index a9afb3f..fc4fd8c 100644
--- a/lib/min_heap.rb
+++ b/lib/min_heap.rb
@@ -69,11 +69,16 @@ def find_parent(index)
   # Time complexity: ?
   # Space complexity: ?
   def heap_up(index)
-    p = find_parent(index)
-    if @store[p].key < @store[index].key
-      swap(p, index)
+    parent_index = find_parent(index)
+    if @store[parent_index].key < @store[index].key
+      swap(parent_index, index)
+      index = parent_index
+    end
+    if index == 0 || @store[parent_index].key <= @store[index].key
+      return
+    else
+      heap_up(index)
     end
-    
   end
 
   # This helper method takes an index and 

From bbf1f2d87cfb71bb1c7973cc3d21f3b714b76fcb Mon Sep 17 00:00:00 2001
From: Nidhi <nidhixpatel@gmail.com>
Date: Thu, 26 Sep 2019 16:23:38 -0700
Subject: [PATCH 4/5] fixed heap up

---
 lib/min_heap.rb | 35 ++++++++++++++++++++++++-----------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/lib/min_heap.rb b/lib/min_heap.rb
index fc4fd8c..ce07a2c 100644
--- a/lib/min_heap.rb
+++ b/lib/min_heap.rb
@@ -20,9 +20,8 @@ def add(key, value = key)
     new_node = HeapNode.new(key, value)
     new_node_index = @store.length
     @store.push(new_node)
-    if @store.length > 1
-      heap_up(@store.length - 1)
-    end
+    heap_up(@store.length - 1)
+    
     return new_node
   end
 
@@ -31,8 +30,12 @@ def add(key, value = key)
   # Time Complexity: ?
   # Space Complexity: ?
   def remove()
-    raise NotImplementedError, "Method not implemented yet..."
-  end
+    removed = @store[0].value
+    swap(0, @store.length - 1)
+    @store.pop(@store.length - 1)
+    heap_down(0)
+    return removed
+  end 
 
 
   # Used for Testing
@@ -69,14 +72,15 @@ def find_parent(index)
   # Time complexity: ?
   # Space complexity: ?
   def heap_up(index)
+    puts to_s
     parent_index = find_parent(index)
-    if @store[parent_index].key < @store[index].key
+    if @store[parent_index].key <= @store[index].key || index == 0
+      return
+    end 
+    if @store[parent_index].key > @store[index].key
+      # puts  @store[index].value
       swap(parent_index, index)
       index = parent_index
-    end
-    if index == 0 || @store[parent_index].key <= @store[index].key
-      return
-    else
       heap_up(index)
     end
   end
@@ -85,7 +89,16 @@ def heap_up(index)
   #  moves it up the heap if it's smaller
   #  than it's parent node.
   def heap_down(index)
-    raise NotImplementedError, "Method not implemented yet..."
+    parent_index = find_parent(index)
+    if @store[parent_index].key < @store[index].key
+      swap(parent_index, index)
+    end
+    if index == 0 || @store[parent_index].key >= @store[index].key
+      return
+    else
+      index = parent_index
+      heap_down(index)
+    end
   end
 
   # If you want a swap method... you're welcome

From c97256982e73ca22e7587f07968090a0984644b0 Mon Sep 17 00:00:00 2001
From: Nidhi <nidhixpatel@gmail.com>
Date: Thu, 26 Sep 2019 16:55:26 -0700
Subject: [PATCH 5/5] working on heap down

---
 lib/heap_sort.rb |  2 --
 lib/min_heap.rb  | 18 +++++++++++-------
 2 files changed, 11 insertions(+), 9 deletions(-)

diff --git a/lib/heap_sort.rb b/lib/heap_sort.rb
index c8a32a4..ca6c499 100644
--- a/lib/heap_sort.rb
+++ b/lib/heap_sort.rb
@@ -1,5 +1,3 @@
-
-
 # This method uses a heap to sort an array.
 # Time Complexity:  ?
 # Space Complexity: ?
diff --git a/lib/min_heap.rb b/lib/min_heap.rb
index ce07a2c..11dbf90 100644
--- a/lib/min_heap.rb
+++ b/lib/min_heap.rb
@@ -32,7 +32,7 @@ def add(key, value = key)
   def remove()
     removed = @store[0].value
     swap(0, @store.length - 1)
-    @store.pop(@store.length - 1)
+    @store.pop
     heap_down(0)
     return removed
   end 
@@ -89,14 +89,18 @@ def heap_up(index)
   #  moves it up the heap if it's smaller
   #  than it's parent node.
   def heap_down(index)
-    parent_index = find_parent(index)
-    if @store[parent_index].key < @store[index].key
-      swap(parent_index, index)
+    puts 'heap down'
+    puts to_s
+    child_index = 2*index + 1
+    if index >= @store.length - 1 || child_index >= @store.length - 1
+      return
     end
-    if index == 0 || @store[parent_index].key >= @store[index].key
+    if @store[child_index].key >= @store[index].key
       return
-    else
-      index = parent_index
+    end 
+    if @store[child_index].key < @store[index].key
+      swap(child_index, index)
+      index = child_index
       heap_down(index)
     end
   end