From bddd188a30a8220123b553452b5923a5bcda22b4 Mon Sep 17 00:00:00 2001
From: Enrique Hilst <enrique.hilst@gmail.com>
Date: Tue, 15 Sep 2020 16:13:41 -0500
Subject: [PATCH] breadth first traversal complete

---
 DataStructures.Tests/TreeTests.cs  | 74 +++++++++++++++++++++++++++++-
 DataStructures/Trees/BinaryTree.cs | 28 +++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)

diff --git a/DataStructures.Tests/TreeTests.cs b/DataStructures.Tests/TreeTests.cs
index e1b6062..646768a 100644
--- a/DataStructures.Tests/TreeTests.cs
+++ b/DataStructures.Tests/TreeTests.cs
@@ -36,6 +36,10 @@ public void Add_can_add_single_Left_and_Right_nodes()
             tree.Add(2);
             tree.Add(7);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+
             //Assert
             Assert.Equal(6, tree.Root.Value);
             Assert.Equal(2, tree.Root.Left.Value);
@@ -54,6 +58,13 @@ public void Contains_can_find_Node_value()
             tree.Add(10);
             tree.Add(1);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \         \
+            //1   3         10
+
+
             // Act
             bool trueResult = tree.Contains(tree.Root, 10);
             bool falseResult = tree.Contains(tree.Root, 11);
@@ -75,6 +86,12 @@ public void PreOrder_returns_values_as_strings()
             tree.Add(10);
             tree.Add(1);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \         \
+            //1   3         10
+
             StringBuilder sb = new StringBuilder();
 
             // Act
@@ -98,6 +115,14 @@ public void InOrder_returns_values_as_strings()
             tree.Add(9);
             tree.Add(20);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \       /  \
+            //1   3     9   10
+            //                \
+            //                 20
+
 
             StringBuilder sb = new StringBuilder();
             sb.Append(" ");
@@ -123,6 +148,14 @@ public void PostOrder_returns_values_as_strings()
             tree.Add(9);
             tree.Add(20);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \       /  \
+            //1   3     9   10
+            //                \
+            //                 20
+
 
             StringBuilder sb = new StringBuilder();
             sb.Append(" ");
@@ -148,14 +181,53 @@ public void FindFindMaxValue_returns_max_int()
             tree.Add(9);
             tree.Add(20);
 
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \       /  \
+            //1   3     9   10
+            //                \
+            //                 20
+
             // Act
             int result = tree.FindMaxValue(tree.Root);
 
             // Assert
             Assert.Equal(20, result);
-
         }
 
+        [Fact]
+        public void Breadth_First_returns_tree_value_in_level_order()
+        {
+            // Arrange
+            BinaryTree tree = new BinaryTree();
+            tree.Add(6);
+            tree.Add(2);
+            tree.Add(7);
+            tree.Add(3);
+            tree.Add(10);
+            tree.Add(1);
+            tree.Add(9);
+            tree.Add(20);
+
+            //    ___6___
+            //   /       \
+            //  2         7
+            // / \         \
+            //1   3         10
+            //             /  \
+            //            9    20
+
+            //Breadth_First list: 6, 2, 7, 1, 3, 10, 9, 20
+
+            // Act
+            IEnumerable<int> result = tree.Breadth_First();
+
+            // Assert
+            int[] expected = new int[] { 6, 2, 7, 1, 3, 10, 9, 20 };
+            Assert.Equal(expected, result);
+
+        }
 
     }
 }
diff --git a/DataStructures/Trees/BinaryTree.cs b/DataStructures/Trees/BinaryTree.cs
index 47b638a..c79bafc 100644
--- a/DataStructures/Trees/BinaryTree.cs
+++ b/DataStructures/Trees/BinaryTree.cs
@@ -24,5 +24,33 @@ public int FindMaxValue(Node current)
 
             return result;
         }
+
+        public IEnumerable<int> Breadth_First() => Breadth_First_Helper(Root);
+
+
+        IEnumerable<int> Breadth_First_Helper(Node current)
+        {
+            if (current == null)
+                yield break;
+
+            Queue<Node> queue = new Queue<Node>();
+            Queue<Node> queueResult = new Queue<Node>();
+
+            queue.Enqueue(current);
+            while (queue.Count > 0)
+            {
+                Node DequeuedNode = queue.Dequeue();
+                queueResult.Enqueue(DequeuedNode);
+
+                if (DequeuedNode.Left != null)
+                    queue.Enqueue(DequeuedNode.Left);
+
+                if (DequeuedNode.Right != null)
+                    queue.Enqueue(DequeuedNode.Right);
+            }
+
+            while (queueResult.Count > 0)
+                yield return queueResult.Dequeue().Value;              
+        }
     }
 }