add min and max binary search tree methods

2 files changed, 42 insertions, 7 deletions

diff --git a/set/set.go b/set/set.go
index 32174bc..29bfad7 100644
--- a/set/set.go
+++ b/set/set.go
@@ -3,8 +3,8 @@ package set
 import "fmt"
 
 var (
-	NotFound       = fmt.Errorf("Could not find entry")
-	NotImplemented = fmt.Errorf("Method not implemented")
+	NotFound       = fmt.Errorf("could not find entry")
+	NotImplemented = fmt.Errorf("method not implemented")
 )
 
 type Set interface {
diff --git a/set/tree.go b/set/tree.go
index 819f83c..3c83f78 100644
--- a/set/tree.go
+++ b/set/tree.go
@@ -65,18 +65,23 @@ func (t *Tree) Del(key int) (int, error) {
 		return n.val, nil
 	default:
 		// I have two childs!
+
+		// Right child has no left child
+		if n.right.left == nil {
+			val := n.val
+			n.right.left = n.left
+			*ptr = n.right
+			return val, nil
+		}
+
 		return 0, NotImplemented
 	}
 }
 
-func (t *Tree) min(ptr **node) (**node, *node, error) {
-	return nil, nil, NotImplemented
-}
-
 func (t *Tree) search(ptr **node, key int) (**node, *node, error) {
 	n := *ptr
 	if n == nil {
-		return ptr, nil, NotFound
+		return nil, nil, NotFound
 	}
 
 	switch {
@@ -88,3 +93,33 @@ func (t *Tree) search(ptr **node, key int) (**node, *node, error) {
 		return ptr, n, nil
 	}
 }
+
+func (t *Tree) min(ptr **node, key int) (**node, *node, error) {
+	n := *ptr
+	if n == nil {
+		return nil, nil, NotFound
+	}
+
+	for {
+		if n.left == nil {
+			return ptr, n, nil
+		}
+		ptr = &n.left
+		n = n.left
+	}
+}
+
+func (t *Tree) max(ptr **node, key int) (**node, *node, error) {
+	n := *ptr
+	if n == nil {
+		return nil, nil, NotFound
+	}
+
+	for {
+		if n.right == nil {
+			return ptr, n, nil
+		}
+		ptr = &n.right
+		n = n.right
+	}
+}