Fix bug for the remove method of BinarySearchTree (aalhour#58)

zhijli · aalhour · commit a92846c5cada · 2018-01-14T21:54:11.000+01:00
diff --git a/DataStructures/Trees/AugmentedBinarySearchTree.cs b/DataStructures/Trees/AugmentedBinarySearchTree.cs
@@ -146,7 +146,7 @@ protected bool _remove(BSTRankedNode<T> node)
 
             if (node.ChildrenCount == 2) // if both children are present
             {
-                var successor = node.RightChild;
+                var successor = _findNextLarger(node);
                 node.Value = successor.Value;
                 return (true && _remove(successor));
             }
diff --git a/DataStructures/Trees/BinarySearchTree.cs b/DataStructures/Trees/BinarySearchTree.cs
@@ -77,6 +77,10 @@ protected virtual void _replaceNodeInParent(BSTNode<T> node, BSTNode<T> newNode
                 else
                     node.Parent.RightChild = newNode;
             }
+            else
+            {
+                Root = newNode;
+            }
 
             if (newNode != null)
                 newNode.Parent = node.Parent;
@@ -96,7 +100,7 @@ protected virtual bool _remove(BSTNode<T> node)
 
             if (node.ChildrenCount == 2) // if both children are present
             {
-                var successor = node.RightChild;
+                var successor = _findNextLarger(node);
                 node.Value = successor.Value;
                 return (true && _remove(successor));
             }

Original file line number	Diff line number	Diff line change
`@@ -146,7 +146,7 @@ protected bool _remove(BSTRankedNode<T> node)`
`146`	`146`
`147`	`147`	`if (node.ChildrenCount == 2) // if both children are present`
`148`	`148`	`{`
`149`		`- var successor = node.RightChild;`
	`149`	`+ var successor = _findNextLarger(node);`
`150`	`150`	`node.Value = successor.Value;`
`151`	`151`	`return (true && _remove(successor));`
`152`	`152`	`}`
Original file line number	Diff line number	Diff line change
`@@ -77,6 +77,10 @@ protected virtual void _replaceNodeInParent(BSTNode<T> node, BSTNode<T> newNode`
`77`	`77`	`else`
`78`	`78`	`node.Parent.RightChild = newNode;`
`79`	`79`	`}`
	`80`	`+ else`
	`81`	`+ {`
	`82`	`+ Root = newNode;`
	`83`	`+ }`
`80`	`84`
`81`	`85`	`if (newNode != null)`
`82`	`86`	`newNode.Parent = node.Parent;`
`@@ -96,7 +100,7 @@ protected virtual bool _remove(BSTNode<T> node)`
`96`	`100`
`97`	`101`	`if (node.ChildrenCount == 2) // if both children are present`
`98`	`102`	`{`
`99`		`- var successor = node.RightChild;`
	`103`	`+ var successor = _findNextLarger(node);`
`100`	`104`	`node.Value = successor.Value;`
`101`	`105`	`return (true && _remove(successor));`
`102`	`106`	`}`